Re:only one thing will really work (Score 2, Informative)

This is the best advice that you will get, and I suggest that you follow it. Last year at my school, somebody gained access to one of the freshmen dorms. Many-a-dumbass in that dorm thought that it was unnecessary to lock their dorms. So this intruder had easy access to rooms and stole from, if memory serves me correctly, upwards of ten unlocked rooms. So just because somebody says "I had my room locked, and I still got stuff stolen" does not mean that its useless to lock your room (and I sure that was not the intended meaning). Your door lock is your first and best line of defense against theft. And on another note, if you're going to have a roommate, you guys should be sure to talk over each other's comfort leveles with regards to the sharing of each other's belongings. That is, if res. life doesn't make you do it to begin with.