One other thing; you shouldn't just memorize how to the problems; rather understand them because the DAT could throw something simpler at you and you wouldn't know how to do it even if you went over destroyer 3 times. I find this piece of advice hard to follow myself sometimes.
I made sure to understand the entire destroyer cold and i got 24's on Gchem and orgo. That was the only source that i used. I woulda gotten higher but i had a couple of wierd questions.