The best way to prepare is to do as many passages as possible.
General reading skills help, but unless you start a year in advance and read consistently you aren't going to move your overall reading level that much.
If you want to do every examkrackers, princeton review, kaplan, verbal passage, under time constraits and go over your answers to each once until you understand your mistake. Figure out the types of questions and how to answer each one.
That way the exact abilities you'll need on the mcat will be developed.
