College student looking for some advice on small business

Background to my background: I just signed up for this site today, aka about an hour ago and I seem to like what I see. Hence I'll ask for advice here since it seems I won't be flamed and the site's subject matter seems to be agreeable with my problem.

Background: I'm a sophomore at UIUC and at the end of last year, (end of spring 2011) I began doing statistics for the Illinois tennis team. Long story short, a year later I developed it into a product that could potentially be a service for many schools across the country.

What I want to know is what kind of advice do people here have for someone who just finished coding what I suppose could be called a "startup" and is ready to go into the open market. I'm not looking to make millions doing this, but with some conservative estimates it could hopefully pay for my tuition. I suppose what I'm looking for is advice as to what some of the major pitfalls of a small business like this might be.

Thank you much for your advice.