If you dont have any science background, you can take kaplan course. But it's expensive though. If you already took gen chem, o chem, and severl biol classes. you can buy destroyer + kaplan book to study. and buy topscore + achiever to practice.
buy crack that pat or use this forum for that section.
Cliffs AP biology, princeton review mcat hyperlearning biological/physical science books (not a must but i thought the bio and gchem was great), CDP, SAT II-math book, Kaplan subject tests, Destroyer (the roadmaps are awesome and it gives you more practice questions to do)
I haven't really used any of the stuff most people use on here like Destroyer for example... for science I used the Kaplan book as a guide to see what topics to learn about (didn't use the info in the book). I took a lot of bio courses for my major (did Biochem) and made tons of good notes over the years which I'm reviewing and for the rest of the stuff that wasn't covered in previous classes I'm looking at an Anatomy/Physiology textbook.
For Chem and Orgo, I also reviewed both textbooks and made sure I understood all the important concepts along with solving a ton of problems... I did pretty well in both classes in school so hopefully the review I did was sufficient.
Haven't taken the DAT yet but we'll see how it plays out, hopefully the material I been reviewing is sufficient relative to all the different study guides people use to prepare.