Yup, keep that door open. Walk down your hall and see what's going on. Go to school events. Football games, soccer games and such. Even if you don't like sports, it's a good way to meet people.
I was generally shy in school, but I got along really well with my roommate and made friends easily. We'd keep our doors open and after awhile people would stop by and say hi, or we'd see people in the hallway doing stuff so we'd go out there too. See what's going on. I met my good friend Mikki when she came into my room to offer help getting the lock off of my cable cord.
Edit: I was glad to be away from home. I saw it as a new start. Maybe look at it that way too
Good luck, and have fun!