I can’t say anything about AP Chem, because I’m taking AP Chem next year as a senior, but I took APUSH as a junior and loved it. I got a 5 on the AP exam and an 800 on the subject test. Pay attention in class, that’s how I learned best. I didn’t actually read the textbook (my teacher didn’t have us outline, we answered paragraph long extended responses for homework and those could be accomplished by googling or asking a classmate for their answer). The best advice I can give you, is to not waste time memorizing super specific facts or dates. APUSH is now a document analysis based class, so memorize trends. Practice making connections between time periods. Those will definitely get you 1-2 points on the DBQ.