reading comp, pat and qr are all practice, practice, practice. i used crack dat pat and i found it to be great. it would buy the 5 tests and do them over and over, and check your answers each time and understand why you got them wrong you should be ok. don't just take the tests and take your scores for what they are, you should find your weaknesses and drill those the hardest.
sciences i used destroyer, kaplan bb, kaplan subject tests, and cliffs ap bio. if you go through the cliffs at least 3 times front and back you're guaranteed a 20 in bio. organic i used destroyer and that was basically it, i got a 20 in that section, but it was my lowest science scores so i cant complain.
gchem i was horrible! i got a 16 my first time and boosted it up to a 22. i used the cliffs college chem a little to brush up and did destroyer 10 times over. i felt it to be a little overkill, but a 22 and no complaints again! the kaplan subject tests were priceless for this section too, try to get your hands on them.