16? wow, congrats.
First, I'll start this by saying, if you want to get into trouble, it will be easy, you can find it anywhere, but at 16, you may be a fish out of water so to speak. Most frosh are to begin with, then throw on your younger age, plus your a commuter, so you're going to be different than the normal student. Its neither good nor bad, per say, just different. I'd recommend limiting the amount of partying you do (if that's your thing). I'll assume your fairly responsible, and it sounds like you have your future pretty well thought out, so this is likely not an issue. I've seen more than 1 frosh drop out of college after 2 semesters of partying hard, and spending little time in the classroom. Its easy to get distracted in college by the social scene that may or may not have been different than what your used to.
With that said, you've got 15 hours, so plan on 15 hours of studying a week (which depending on the classes may be way more than you need or not enough) that's 30 hours of your week chaulked up. I'll agree with others about getting involved in clubs or something on campus. I wish I had done that more, its a great way to meet people with similar interests. However your still going to have free time.
My advice, is to get down to the career services and see if they have any sort of connections to local companies that could use 10-20 hours a week of help in something related to your field. Or even if its not in your field, there is usually a lot of student jobs around campus, some that require little more than answering a phone and allow you to study b/w calls. Point is, get work experience that you can add to your resume. Even better if its in your field. Even if its for minimum wage, or no money at all, that experience will put you a step ahead of other people in your field 2-3-4 years down the line.
Depending on your financial situation, given your age, I'd recommend to take things a little slower, 5 or 6 years, but as many internships or field related work experience as you can get. I'd look into the study abroad program, and start planning now to spend a semester taking classes in another country, preferrably somewhere where their language (I'm thinking spain) could be advantage to your potential law enforcment carreer.
good luck, enjoy.