For the QR, I started with Destroyer and got destroyed by it. I slowly started figuring out and becoming better at common problems everybody can expect (rolling dice, and other probability, and questions like "mark can paint a wall in 2 hours, John can paint in 3, how long if they work together?", combinations and permutations, questions like martha is 3 years older than her sister.... in 14 years she will be 5 years older than twice her sisters age". Go through destroyer UNTIMED and learn how to do the common problems! Then after doing just about half of the destroyer go through bootcamp and try to hit 20's on all the exams. The comparison problems on there are great practice.
For the rest of the DAT, I used Cliff's and Feralis for bio. Chad's videos for G chem and O chem first and foremost. I can't stress Bootcamp enough, amazing for the sciences, math, PAT, everything. Went through destroyer sciences a bit but the real thing was much much much easier in gen chem and o chem than destroyer and even slightly easier than BC.