Do you mean before you enroll? I would make sure to look into housing and make sure the type I want is available. I would make sure that I could own a car while living in the dorms. I would make sure that the school has a reputation for being safe, especially if I'm living on campus and will be out at night. I would also look up reviews of your intended major program.
One thing that is a good idea is to come and stay over a weekend. Most schools have programs where prospective students can be paired with current students for a night or a weekend to learn about the culture of the school. The weekend will tell you how much of a party school it is and if people stay on campus for the weekends, things like that that important if you are going to be there for four years.
I wish I had met my roommate before I moved into the dorm. It would have made a world of difference in my first college experience. Somehow or other, the college missed getting the addresses out. Also, having a friend go to the same college would be a great idea.