Joe pretty much covered it. I will second the idea about an advisor. If the other side says you don't need one, then you do. My son's advisor helped him and us tremendously (and still does even though he is in college). After the first couple of visits, we could have filled out a form as all the teams were very similar, ask the same questions, etc, etc. It was an enjoyable, yet stressing, experience.
One other piece of advice that we were given was to set a cut off date (ours was a date in January) so the visits did not progress through the baseball season. We also chose one night a week and tried to see two in an evening so that several evenings were not occupied.