I will post the easier challenges in order to obtain the two challenge achievements :
1) Catch 5 bugs/butterflies / You will find plenty of insects and butterflies outside your house and in the parks around the city .
2) Buy your first computer / Go to the buy catalogue and buy your first computer . Cheaper one is 800 simoleons .
3) Complete each skill to level 10 / They are 10 skills which you have to complete to level 10 , each completed skill gives you a challenge point.
4) Write your first novel / Just go to your computer and select the option write and choose any kind of novel to finish.
5) Tour the city hall / Open your town map find the city hall and select tour .
6) Watch a game / Again go to your town map , find the stadium and at Wednesday at 15pm attend a game .
7) Fill your karma meter / Just don't use your karma meter at all until it reaches 100 and the challenge is yours
8) Use epic fail in 10 different sims / You will need 325 karma points in total to get this challenge and achievement . You have to unlock the epic fail karma power and use it on 10 different sims
9) First Kiss / Find a sim of your interest and start socializing until the green social bar is full , just make sure you are using romantic interest instead of friendly . When the bar is full just try and kiss the sim and the challenge is yours .
10) Read any non skillful books (novels) / Go to the bookstore and start purchasing novels. Each novel you complete reading there is a challenge point. They are up to 15 books in total .
11) Get into level 5 into each job available / They are 18 jobs in total that you can access through your computer or the map , Each job you reach level 5 you get 1 challenge point. More sims means faster collection of challenges especially for this one .
12) Collect your first collectable rock / Just go out in parks or outside your yard and search for stones . If you find one collect it and 1 point is yours .
13) Fish perfect unique species / This is easy if you have level 10 fishing skill . They are about 45 different fish in different locations . Each perfect unique fish you get means a challenge point .
14) Go to a date / Just call a sim and invite him/her anywhere in the town map .
15) Paint your first painting / Go to the buying catalogue and buy an Artsy Easel . When you do that start painting a small painting which is faster to complete , so you can get the challenge point faster .
16) Get a raise / this will unlock in your effort to level your job positions . Each level of your job means promotion so this challenge may come without you noticing it :)
17) Grow perfect plants / They are about 20 different plants and you need to buy or find the seeds from parks or from outside your yard. To grow a perfect plant you need to be level 10 gardener and then you go to your inventory on build mode, you find your seed and plant them anywhere in your yard. Make sure you fertilize them with perfect quality fish or fruits
18) Duck time / Go to the supermarket on the town map , and buy a yellow duck . When you buy it go home open your inventory and place the duck in the bathroom and bathe your self .
19) If you are a computer wiz hack with your computer 10 times .You can change your lifetime wish by buying the life trait for 20000 wish points and get the computer wiz trait to help you complete the challlenge.
20) Train your toddler / When you decide to have a baby , you will need to train you toddler. they are 3 different lessons each one providing with a challenge point. The first lesson is train your sim to walk , the second to talk and the third to use the toilet . For the toilet you will need to teach him/her walking first and then buy a baby toilet from the catalogue .
21) Visit the art gallery / Open your map and find the art gallery is called artsy...something :P click on the gallery and tour it .
22) Tour the military base / Go again to the world map and find the military base and tour it .
23) Throw a birthday party party/Blow off the cake / These are two challenges and you can do it with your baby sim which is turning into a child . First call lots of friends and ivite them for a party/birthday party . When you do that go to the buy option and buy a cake from the entertainment tab .Open your music system make some drinks and wait for the guests . When the guests arrive make your baby to blow the candles from the cake and watch him grow to a child ,then you get the first challenge . Then let your guests leave the house satisfied from the party and another one challenge is yours .
24) As a child do your homework / When you turn to a child you will start going to school , when the kid returns from the school open your inventory and find your homework and do it .
25) Buy every business property / When you get a lot of money start becoming a partner to shops and businesses and then buy the property from them. Every property is one challenge .
26) Shotgun wedding / Married while pregnant or marry a pregnant sim .
27) Visit the mausoleum / Open your map find the mausoleum and tour it :)
28) Interact with a ghost / Open your map and find the mausoleum and visit it at midnight . Find a ghost and talk to it .
29) For every different genre of a novel/book you write you get one challenge point. They are in total 15 different novel you can write . Just open your pc go to write and every time choose a different genre until you complete all 15 of em .
I think these challenges are more from 150 . If you need help dont hesitate to pm me or comment on my solution .
Good luck :)