In General and Organic Chemistry, I basically started off with concepts. Reading and rereading and then just making sure I understood everything because a lot of it is concepts. For the other stuff, I had an old gen and o chem book and would do a small number of practice problems for the basic types of problems. From there, I went to kaplan, topscore, and achiever. I also read the kaplan book on those sections multiple times.
QR: Practice. Didn't do much of it.
RC: Did 4 practice tests. Didn't do much more than that.
PAT: Practice, practice, practice. Again, Topscore, kaplan, achiever for me.
Bio: The big one for me. I read kaplan's blue book about four or five times. Read schaum's twice including the practice questions. They help a lot. Besides that, and yes, you guessed it, more practice problems on kaplan, topscore, and achiever.
Additional information: There are some helpful threads with some good questions. I used those as well.