This is going to sound really dumb, but I thought this was critical for my success (I got a 23 on the RC).
Like any skill, you have to practice, and reading is not any different. I would suggest reading a little bit for pleasure, or even better, pick up a newspaper and scan it.
I didn't think that the DAT asked nit-picky details, so you should really try to train yourself to be alert of "interesting" facts and figures and not worry too much about the finer points (but try to remember it's location, both in context and where it is on the page, so that if you do get asked a more detailed question, you know where to look).
Hope this helps. Sorry that it isn't exactly the secret technique or anything special.