A friend of mine who is attending dental school at Oregon gave me far and away the best advice I received for reading comprehension. This advice will probably seem obvious to you, but keeping it in mind helped me score extremely well.
He told me this: FOCUS. Tell yourself ahead of time that you are going to have laser-sharp focus and concentration during reading comprehension, especially on test day. It is a mind game, and you must get psyched up for it. For the science sections of the DAT, focus is important, but chances are you will have memorized most of the material and will be able to just plug in your answers (especially for biology and organic chemistry). For reading comprehension, however, you must exert all your efforts toward memorizing (as much as possible) the structure of the passages you are given, and toward understanding what they are saying. I'm not the greatest reader, but having absolutely laser-sharp focus allowed me to score very highly on this section with very little practice. For you, Comet, with English being your second language, you are going to have to focus all the more intently.
That being said, it's also absolutely essential that you have spent time practicing a method for jotting down the structure of the reading passages you are given. Write down a main idea or two from each paragraph so that you can jump back to them and refer to them when you are given a question. For me, taking good notes on the structure and having intense focus on remembering what was where made it easy to locate the answers for each question. Keep in mind that very few questions you will be given will require you to analyze or make inferences. It's basically a game of hide-and-seek - how fast can you locate the facts?
I hope this helps you out in your prep. Good luck!
