my recommendation would be buy the kaplan book study everything, in and out, but dont' take the course its really a waste.
then buy the dat destroyer and study everything in and out, you'll be shocked to see that alot of questions you are unable to do, but don't worry everything will be fine....its a GREATTTTTTTTTT book, you will learn alot.
then if you wanna score high buy both top score and achiever...again, alot of questions you wont be able to do cause its very hard, but don't worry because the test is not as hard, its actually way easier.
i would defenitly recommend barrron's number one for DAT....defenitly for preceptual ability and some of the math problems.
i honestly have studied this way....you can prove your reading buy buying some hard scientific books and just read it.
p.s. forgot to mention when to study....if you are applying for next year...defenitly don't take the DAT after august....August is good...some schools say they want the score no later than october but i would defenitly recommend no later than august....but make sure you are ready for the test, its better for you to get a good score and go one more year later than rush it out
my Best wishes to you!!