This is the only part of the test that I feel you can't really prepare for. If you're deficient at reading, it's going to be impossible to get up to speed in a practical timeframe. If you're already a good reader, there's not much you can do to get ready. Just try a few practice passages from Kaplan to get your pace and timing straight. I set my pace to complete reading each essay within 7 minutes. That leaves you with 13 minutes to answer questions for each one. You have to read at a decent pace but not speedread, so that you can remember stuff you read and maybe where it was located. If you get tripped up by a confusing sentence, keep going. There may not even be a question about that point. Hopefully there will be one passage that you find easy and familiar (to make up some time), b/c there will probably be one that you find very hard too (and lose some time). I did not read the questions beforehand as some people suggest. Definately don't be afraid to utilize the skipping feature for questions you can't rapidly answer either. If you kind of know it but have to search, fine. If you have no clue and a cursory search turns up nothing, move on. My philosophy worked very well for me but it's best to stick with however you like to do it. That will always work best for you.
And don't practice on journal articles. They're too in depth and complicated. Get practice DAT passages from wherever you can.