Solution update 21/3/17: Added a second leveling up method as people have mentioned that the first method doesn't work with 'Sam B' Second method works with all characters. Also added a warning to players with maxed out RAGE duration.Warning! (depending on your character strength) if you max out the duration meter in the RAGE skill tree, you mite end up killing Ryder too quickly, causing you to earn the Xp after the cut scene and not before. Which means for anyone passing from level 49-50 will not earn thier achievement as the game won't register that you hit level 50. From what Iv seen , it's only more common with players using Xian.
If you haven't maxed out the rage meter then only level it up twice and no further then that.
If you have already maxed it out it's still possible to earn the achievement. You'll want to firstly make a back up save when you hit level 49. Then progress through lvl 49 using the method below until your Xp bar is near enough full. Then either proceed to kill Ryder using any other method except RAGE or load up your characters save in a different chapter and just earn the last of the Xp you need doing quest. Method 1
Similar or somewhat the same as the old method on the 360 version where you just beat Rider White at the end of the game with your Rage ability to give you a massive stack of xp.
First BEAT THE GAME!
After beating it, select new game and choose the character you finished the game with, then select Chapter 18.
Then it will ask you to choose a save. Use your main character save (should be the save closest to the top)
Now this will load you up on the final fight with Rider White.
Simply fight off the army guys and the zombies until your Rage meter is full, after that head to the heli-pad to fight Ryder and kill him with your Rage ability.
This will give you tons of xp and is a very effective way to Rank up fast!
Here is a video I made for example. After killing him I earned 60,000xp Although I was level 51 so depending on what level you are, xp my be different, for example if your level 40 Youll probably earn about 30-40k for killing him. I also hit a 4x multiplier while I kill him in RAGE, if your finding it difficult to get a 4x multi then you need to upgrade your duration and damage in the skill tree.
The making a new game method works also with money
I found that if you are running low on cash, load up chapter 14 where it will load you up in the Laboratory.
There will be missions finished that you can collect money from.
Simply collect the money, quit the game and repeat. This way you can constantly earn money for things like medkits, ammo, repairs etc.
I have also made a clip for this for example.
This leveling up method can be done using a Continuous quest 'time for booze' where you have to give this drunken Russian lady 'Brand Champagne'. In exchange she will give you 1000xp and diamonds for each bottle you give her. This quest can be found as early as Chapter 3. You'll also need to use a duplication glitch to get yourself 100s of bottles.
First things first you'll need to be on:
Chapter 3: Wheels of Steel
Quest: Born to be Wild (Talk to Sinamoi)
If you have just started then keep playing the game until you reach this point, for people that have past this Chapter or beat the game, you can go to Character select 'New game' select the character you've been playing with, then go on 'Chapter 3' it will then ask you to select a save, click on the main character save you have been using (the save closest to the top) Then when you spawn in you should be outside Sinamois room. Step 1: Getting Brand Champagne
Your going to need 'Brand Champagne', you can only get this item in Chapter 3 and The super market chapter later on in the game.If you already have Champagne:
Talk to Sinamoi and accepts his quest, then it will save so that everytime you reload the Chapter you'll spawn outside the room Sinamoi is in. we need that so that the glitch will work, read further down to find step 2. If you don't have Champagne:
You'll need to accept Sinamois quest where he will ask you to go into the hotel to get the truck. In the kitchen area of the hotel, in the fridges you'll find your Champagne, try loot as many as you can.
Here is a clip that shows where to find the Brand champagne in the Hotel. Once you have the bottle/s, you can save and quit to main menu and reload chapter 3.
Once you have reloaded Chapter 3, talk to Sinamoi again and accept his quest, this way it will save the game so every time you reload the Chapter you'll always spawn outside the room where Sinamoi is. If you already had Champagne then all you had to do is talk to him and accept his quest so it saves.Step 2: Duplicating the bottles
Now comes the duplication Glitch. What your going to be doing now is duplicating bottles over and over again until you feel like you have enough to rank to 50. Note that the duplication glitch works with all items including weapons and crafting materials.
I will explain how it works in text and in a clip.
Once you have accepted the quest and it saves, you can drop the items you want to duplicate.
Then after you have done that you must run to the back of the building where the railing is and jump of the edge, the fall should kill you but as soon as you die you must instantly hit start and reload checkpoint!
Then as soon as you spawn you'll notice the items you dropped on the floor will still be where you left them but if you also check your inventory, all the items will be back in your inventory as if you never dropped them so you should be left with double the items!! This is where the Champagne trick come in! Say if you dropped 2 bottles then killed yourself and reloaded checkpoint, you should be left with 4 bottles, then do it again and it doubles and keeps going and going.
Here is a clip that will teach you how to use the duplication glitch.
Step 3: Continuous Quest (Time for Booze) Getting the XP
When you feel you have enough champagne, the next thing is finding the Quest to get the XP.
The Quest can be found on the top right of the Island, The quest giver will be in a hut with some other pissed up people, you'll know its her as she demands that she must get drunk!
When you accept the quest you can keep giving her the bottles and she will give you 1000xp and diamonds everytime! These diamonds can also be sold for $1000 dollars each. So not only are you going to be level 50, you'll also be million dollars richer!
This clip will show you the location and me giving her the bottles that I duplicated.
If you feel the solutions don't make much sense or needs alterations, feel free to leave your opinions in the comments.
I'm not a master at making solutions and would much appreciate feedback to make them better.