How to self-study for AP exams?

Next Year I will be taking: AP Human Geography, U.S. Government, and Macro Economics. However, I was considering self studying for Comparative Government and possibly Environmental Science. Do you think this is a good idea? What are good methods for Self-studing, and when should I begin? Thank you for taking the time to read this.

Would this be possible considering I am taking: Advanced American Literature, Chemistry/Biology, Algebra 2/ Geometry and French 2 in addition. For Extracurricular I have: FBLA, International Relations, Golf( in the fall, practice in spring), Trying to establish a foundation, Avation, Boy scouts, Cello, Hospital volunteering, and Academic Decathlon.
Thank you for taking the time to read this.

I also don’t mind not having any free time, don’t have any now.

@cj5555
I think the key to self studying is to be interested in the topic. You are already taking 3 AP’s, so it will be a lot. I think you should focus on grades in your actual courses and focus on ECs. Not to mention the three AP exams you’re enrolled in. I don’t know your schedule and time management skills exactly, but I would definitely advise against self studying two AP’s.
There’s also SAT/PSAT/ACT to worry about…