Does anybody know any resources for effective studying methods and strategies?

for more context: i have to take an exam in 6 months or so. this exam covers around 16 college courses (mostly math and computer science related), has around 120 4-choice questions and 4 hour time to answer, so a little over 2 minutes per question. the questions are around half split between problem solving and memorizing.

for a few of the subjects i probably already know most of their content, and a couple i couldn't understand from the start but the majority of them were ones that i've studied at some point but have forgotten now.

so my question is how the hell can i prepare myself as best as i can in the little time i got? what i need are some resources to help me plan my study sessions and how i would go about studying, and also how to take mock exams from myself. any other tip is also appreciated.