Of the other two solutions posted here at the moment, I feel one has too little information, and one is too messy, so I took it upon myself to write down where all the things in the journal can be found. No offense to the other solution writers (their solutions helped me after all), but I consider this the definitive solution for this achievement.
So, first off, you can check your journal anytime in-game by pressing the back button, and you can check which entries you are missing by simply scrolling through everything and seeing which entries are blank.
For places, you just need to visit them once.
For monsters, you either have to kill or be killed by one to get it to count.
For traps, some count as soon as they activate, but for most you either have to let them kill you or destroy them.
Since I foolishly missed a Succubus on my Yama-killing trip to Hell, I had to make an extra run there, so here are all the journal entries exclusive to that area, just so you don't miss anything.
Places: Hell (duh...)
Monsters: Entries 50-56, also don't forget to kill Anubis II in the City of Gold.
Items: Vlad's Cape and Vlad's Amulet, you'll also pick up the Book of the Dead in the City of Gold.
Traps: Spike Balls
And here is the full list of all journal entries.
1. Mines - Unlocked the first time you start the game
2. Jungle - Unlocked when you reach the Jungle, after the Mines.
3. Ice Caves - Unlocked when you reach the Ice Caves, after the Jungle.
4. Temple - Unlocked when you reach the Temple, after the Ice Caves.
5. Hell - Unlocked when you reach Hell, the entrance to which can only be found if you collect the Book of the Dead in the City of Gold, then use it to find the entrance to Hell in Olmec's Lair (the book laughs/shakes when you are more or less directly above it). Olmec has to land under the exit for you to be able to step on his head and enter, so make a hole with bombs or a Mattock.
6. Haunted Castle - Unlocked when you reach the Haunted Castle, the entrance to which is found by bombing underneath the grave containing a skeleton with a crown that can be found during the random "The dead are restless" event on Jungle levels.
7. Black Market - Unlocked when you reach the Black Market, by acquiring the Udjat Eye in the Mines and finding the secret entrance somewhere in the Jungle (the eye will flash faster and faster the closer you are to it).
8. Worm - Unlocked by reaching the Worm area, which is found by throwing a Damsel into one of the orange/pink blobs you can sometimes see stuck to walls in the Jungle and Ice Caves. Then you yourself must jump into it and wait a few seconds for the worm to come eat you, after which you'll be inside it.
9. Mothership - Unlocked by reaching the Mothership area, which is found by entering the door inside the spaceship during the "Feels like the fourth of July" event on an Ice Cave level.
10. City of Gold - Unlocked by reaching the City of Gold. First, you must purchase or steal the Ankh from the Black Market. Then you must die close to the giant blue stone head in the Ice Caves (usually on the second level). This will give you the Hedjet helm. Now get the Sceptre from killing Anubis in Temple level 1, and carry it with you to the golden door in Temple level 2 to unlock it and reach the City of Gold.
1. Snake - Found everywhere in the Mines.
2. Cobra - Found on Mine levels, looks like a blue hooded snake and spits poison.
3. Bat - Found everywhere in the Mines and Jungle.
4. Spider - Found hanging from the ceiling in the Mines. They drop down when you walk underneath them.
5. Spinner Spider - Spiders with a purple body that hang from the ceiling and go up and down. Found in the later Mine levels.
6. Giant Spider - Found in the later Mine levels and more commonly during the "My skin is crawling" random event. Best killed with sticky bombs.
7. Skeleton - Found throughout the Mines and the rest of the game. Some of the bone piles you come across will randomly become a Skeleton when you walk near them.
8. Scorpion - Yellow scorpion found in the later Mine levels and more commonly in the Jungle and Temple.
9. Caveman - Sometimes found in the Mines, but more commonly in the Jungle and Temple.
10. Damsel - Found on almost any level, you might have to kill one to put her in the journal.
11. Shopkeeper - Found in any shop. Most easily killed with a shotgun or well placed Sticky Bombs.
12. Tunnel Man - First encountered at the end of the Mine levels, in the transition to the Jungle.
13. Scarab - Yellow bugs found flying around in the randomly appearing dark levels, and also in the City of Gold. They don't hurt you and can in fact be collected for 5000 gold, so only kill the first one you see to put it in your journal.
14. Tiki Man - Found throughout the Jungle, looks like a Caveman with a Tiki mask, and is usually carrying a boomerang.
15. Frog - The blue kind of frog found throughout the jungle.
16. Fire Frog - The red-orange kind of frog found throughout the Jungle. Explodes shortly after it dies.
17. Giant Frog - A big blue frog found randomly in the Jungle. Spits out smaller frogs.
18. Mantrap - A red flesh-eating plant found in the Jungle. Touching it means instant death.
19. Piranha - Bigger fish (bigger than the tiniest ones, that is) found in the water pools in the Jungle.
20. Old Bitey - A much bigger piranha that appears during the random "I hear rushing water" event on a Jungle level. It'll be in the big pool at the bottom of the level.
Tip for Old Bitey (credit to SkepticalMario): It's simple enough to clear the upper area by jumping in, whipping a few piranha, and jumping back out. When Bitey is the closest fish, jump back in and let him eat you. (Disclaimer: not sure how much damage he does.)
21. Killer Bee - Bees with blue eyes encountered when a bee hive randomly spawns on a Jungle level.
22. Queen bee - Bigger bee with red eyes ecountered when a bee hive randomly spawns on a Jungle level. One sticky bomb is enough.
23. Snail - Found throughout the Jungle. Spit out acid bubbles that float up toward the ceiling.
24. Monkey - Found throughout the Jungle, most commonly wherever there are green vines. They steal gold/rope/bombs from you, and sometimes knocks you out for a painfully long time.
25. Golden Monkey - Appears when you sacrifice an Idol to a shrine to Kali. Requires a bit of luck and planning, but you should eventually run into a spot where the two things are fairly close to each other. Just make sure the Idol trap (if it's a boulder) doesn't destroy the Kali shrine.
26. Jiang Shi - Zombies in purple robes encountered during the random "The dead are restless" event in the Jungle, and also everywhere in Hell.
27. Green Knight - Encountered in the Haunted Castle area.
28. Black Knight - Encountered at the top of the castle in the Haunted Castle area.
29. Vampire - Encountered hanging from the ceiling in bat form during the random "The dead are restless" event in the Jungle, and everywhere in Hell as well.
30. Ghost - Appears when time runs out on any level, or if you steal the skull Idol during a "The dead are restless" event. Let it kill you once to put it in the journal.
31. Bacterium - Found traveling along the walls in the Worm area.
32. Worm Egg - Found attached to walls in the Worm area. They will burst soon after you come near them, but you have to destroy one yourself to put it in the journal.
33. Worm Baby - Emerges from the Worm Eggs in the Worm area.
34. Yeti - Appears on Ice Cave levels.
35. Yeti King - Appears during the random "It smells like wet fur in here" event on an Ice Cave level.
36. Mammoth - Appears on Ice Cave levels.
37. Alien - Emerges from destroyed UFOs found flying around on Ice Cave levels.
38. UFO - Appears on most Ice Levels.
39. Alien Tank - Appears all throughout the Mothership area.
40. Alien Lord - Appears during the random "I sense a psychic presence here" events on an Ice Cave level. He's located at the very back (right side) of the spaceship. Also appears in the Mothership, usually close to the Alien Queen.
41. Alien Queen - Appears at the top of the Mothership area, and can attack from a distance with her crosshair attack. I'd suggest playing it as safe as possible and just using lots of bombs and possibly a shotgun.
42. Hawk Man - Red birdmen encountered in the Temple.
43. Croc Man - Crodcodile-headed men found in the Temple. Can telefrag you randomly, so it's highly advised you completely avoid them.
44. Magma Man - Found rarely in the Jungle when a "Tiki village" spawns on a level, they jump out of the little cooking pots in the houses. More commonly found jumping out of lava in the Temple and Hell.
45. Scorpion Fly - Flying red scorpions found in the Temple.
46. Mummy - Found in the Temple and the City of Gold.
47. Anubis - Always found flying around on the first Temple level. Can sometimes pass through walls, and shoots dangerous purple orbs, but fairly easy to kill with a shotgun or sticky bombs.
48. Anubis II - Appears when you collect the Book of the Dead in the City of Gold. Summons lots of red skeletons (they don't count for a journal entry), but thankfully doesn't shoot purple orbs like his predecessor.
49. Olmec - The boss encountered at the end of the Temple area. Easy enough if you have enough bombs to make a pit for him to fall into. Otherwise you can run back and forth underneath him and let him dig his own grave.
50. Vlad - A stronger vampire found at the top of the tower on one side of the first level of Hell.
51. Imp - Red demons found flying around carrying lava pots in Hell.
52. Devil - Blue demons (basically a caveman variation) found in hell. The spikes on their heads might make them dangerous to head stomp, but I haven't tried.
53. Succubus - Appears in Hell disguised as a Damsel/Dude/Pug. Lunges at you when you get near, so not that hard to distinguish from the real Damsel.
54. Horse Head - Appears on the left side of the level at the start of the Yama fight. Easily killed with a shotgun or bomb.
55. Ox Face - Appears on the right side of the level at the start of the Yama fight. Easily killed with a shotgun or bomb.
56. King Yama - The final boss of Hell. Actually not that hard if you take your time with him. Stay in one of the top corners (underneath the bricks where his falling skulls can't hit you) and throw sticky bombs (Horse Head/Ox Face each drop a bomb box) at his hands until they blow up and his head starts flying from side to side. Whenever it flies to your side, throw one or two stickies diagonally up to hit it, and he should die fairly soon. Shotgun works too.
1. Rope Pile - Found in crates or shops.
2. Bomb Bag - Found in crates or shops.
3. Bomb Box - Commonly found in shops and sometimes crates.
4. Spectacles - Commonly found in shops and sometimes crates. Can also be a gift from Kali.
5. Climbing Gloves - Commonly found in shops and sometimes crates. Can also be a gift from Kali.
6. Pitcher's Mitt - Commonly found in shops and sometimes crates. Can also be a gift from Kali.
7. Spring Shoes - Commonly found in shops and sometimes crates. Dropped by Giant Frogs in the Jungle. Can also be a gift from Kali.
8. Spike Shoes - Commonly found in shops and sometimes crates. Dropped by the Yeti King in the Ice Caves. Can also be a gift from Kali.
9. Paste - Commonly found in shops, usually alongside Bomb Bags/Boxes. Dropped by Giant Spiders in the Mines.
10. Compass - Commonly found in shops or crates. Always dropped by the Yeti King in the Ice Caves. Can also be a gift from Kali.
11. Mattock - Found in shops and sometimes crates. Also appears at the bottom (bomb it out of the ground) of the snake pit during random "I hear snakes, I hate snakes" events on Mine levels.
12. Boomerang - Found in shops or crates. Carried by Tiki Men in the Jungle.
13. Machete - Commonly found in shops and crates.
14. Crysknife - Found in one of the acid pools in the Work area. It's advised you drain the acid first by blowing up one of the walls.
15. Web Gun - Commonly found in shops and crates.
16. Shotgun - Commonly found in shops and sometimes in crates. Carried by Shopkeepers. Also, during "The dead are restless events" in the Jungle, one can almost always be found buried under a gravestone with the name ASH on it. You SHOULD get that reference.
17. Freeze Ray - Commonly found in shops and sometimes crates.
18. Plasma Cannon - Located just underneath the Alien Queen in the Mothership area. Just kill her and bomb it out of there.
19. Camera - Found in shops and crates.
20. Teleporter - Found in shops and sometimes crates.
21. Parachute - Found in shops and crates.
22. Cape - Found in shops and dropped by Vampires during random "The dead are restless" events on Jungle levels or in Hell.
23. Jetpack - Found in shops and rarely in crates.
24. Shield - Dropped by the Black Knight in the Haunted Castle area.
25. Royal Jelly - Dropped by a Queen Bee that appears in randomly spawning beehives on Jungle levels.
26. Idol - Gold head statues found at booby-trapped altars on many levels. You only need to pick it up to put it in the journal.
27. Kapala - Acquired by making enough sacrifices to Kali in one playthrough to get your "Kali favour" up to 16. A Damsel is worth 12, so two of those will do it.
28. Udjat Eye - Found in gold chests in the mines, the ones that require a golden key (always found somewhere else on the same level) to open.
29. Ankh - Bought (or stolen) from the southeastern-most shop of the Black Market for 50,000 gold.
30. Hedjet - Found by getting the Ankh, then dying near the giant blue stone head that appears on level 2-3 of the Ice Caves.
31. Sceptre - Dropped by Anubis on the first Temple level.
32. Book of the Dead - Found on an altar in the City of Gold. You usually have to bomb to get in there, and Anubis II appears when you pick it up.
33. Vlad's Cape - Dropped by the vampire Vlad, who appears at the top of the tower on one side of the first Hell level.
34. Vlad's Amulet - Found just below where Vlad hangs. Use a bomb to get it out of the wall. It comes in very handy since it lets you run right through Magma Men.
1. Spikes - Found almost everywhere. Kills you instantly if you land on them but can be walked through and landed on safely with a cape.
2. Arrow trap - Found everywhere in the Mines and Temple. Shoots an arrow when something crosses its line of sight.
3. Powder Box - Explosive boxes with a red skull on them. Found in the Mines. Let one kill you.
4. Boulder - Appears when you steal an Idol from an altar in the Mines. Just let it crush you.
5. Tiki Trap - Found everywhere in the Jungle, Temple and Hell. Red-brown statues with spikes that shoot out from its sides.
6. Acid - You can find pools of this only in the Worm area. Simply jump into it and let it hurt you to put it in the journal.
7. Spring - Found on the ground throughout the Ice Caves. Quite hard to see, but easy to spot if an enemy gets stuck in it.
8. Mine - Grey circles with a big red button on, found everywhere in the Ice Caves. You only have to activate it to put it in the journal, no need to let it kill you!
9. Turret - Appears during the random "I sense a psychic presence here" events on an Ice Cave level, and in the Mothership.
10. Force Field - Appears during the random "I sense a psychic presence here" events on an Ice Cave level, and in the Mothership. They look like big purple lasers.
11. Crush Trap - Grey blocks with an eye on them that appears in the Temple. Causing one to drop/rise is enough to put it in the journal.
12. Ceiling Trap - Activates when you collect an Idol in the Temple. Actually pathetically easy to avoid if you know it's coming, and it gets put in the journal as soon as it activates.
13. Spike Balls - Spiky balls on long spinning chains found everywhere in Hell. Blow up the block the chain is attached to to put it in your journal, but be careful since the ball will go flying!
14. Lava - Found in the Temple and Hell. Instant death.
So there you go. If anything is unclear, just leave a comment or send me a message and I'll try to help you :)