russiancub definitely knows what he's talking about.
establish a good foundation for your gen chem before tackling the DAT Destroyer. Theres tons of materials out there and by all means, I'm using TS, Achiever, Kaplan, & Destroyer. Destroyer will help you master all the sections once you've got solid knowledge of them. Nancy & Dr. R are so helpful that you are definitely missing out if you don't have a copy of the book.
good luck!