How to maintain my natural hair? 10 pts?

So, i am african american and i have verryyyy thick hair. My mom doesnt really know how to maintain it herself, but she doesnt trust me to do it. I usually press it, and my flat iron is 350 degrees. Even with that, i go to school with a puff ball on my head. Thanks to my mom, i get my hair washed about every 3 weeks (ikr...nasty). And for this school year i really want to look appropriate for school. Im already investing in a Chi flat iron but i need to know what specific products to use.....and it has to work for african hair that has never had any chemicals in it. I really need everything i need to use...down to the brand name. Please and thank you.