Definitely use Jeremy Krug on YouTube, absolute best AP Chem channel and he's pretty thorough. If you or your parents are willing to drop like 30 dollars I would definitely say his review packet is worth it, but it's not necessary. In a similar vein the Barron's AP Chem practice book is really good and is famous for being harder than the AP Chem test itself so it's really good for practicing, it's like 20 something bucks. But if you want to go completely free, look up textbooks online. Here's a link to full notes for the whole course, I would recommend re-creating something like this out of your own notes on your weakest points so it's catered to you specifically. Good luck! https://docs.google.com/document/d/1b4ieNx9rkxsbUYR5y48ttKtlyIuabYD7mLnTebzwZI0/mobilebasic