1. Clean up after Yourself
If you make a mess, you should clean up after yourself. Don't leave your clothes on his floor. Don't leave your hair in his bathtub. It doesn't matter if his room is already messy. You should still be respectful by cleaning up after yourself.
2. Don’t Leave Your Clothes There
Eventually, you'll have a toothbrush and extra pair of clothes at his house. But for now, you shouldn't bring over those items and throw them in his closet. Wait until he offers. Once he gives you permission to leave half of your house at his house--or even better, gives you a spare house key--you can bring over as much stuff as you'd like.
3. Don’t Use His Stuff without Asking
Don't steal his pajamas without asking first. If it's still early on in the relationship, you should always ask him if he has something that you can borrow instead of just taking it out of his closet. He probably doesn't want you rummaging through his room.
4. Don’t Overstay Your Welcome
Ask your boyfriend if he has anything he needs to do during the day. If he has plans in the afternoon, then you should leave before he needs to leave. Even though he invited you to stay the night, it doesn't mean he wanted you to stay over for all of the next day. Don't overstay your welcome.
5. Volunteer to Help with the Dishes
If he cooks you dinner, volunteer to help him out. Once dinner is over, volunteer to help him with the dishes. It's rude to just sit there while he does all of the work for you. The least you can do is ask if he needs any help. With any luck, he'll tell you that he can handle it and you won't be stuck helping, anyway.
6. Respect the Others Living There
If he lives with his parents, you shouldn't walk around his house in your underwear. His mother certainly doesn't want to see that. If he owns a dog or a cat, make sure you treat it well. If you push it away whenever it comes near you, your boyfriend probably won't want you around for long.
7. Don’t Make Too Much Noise
If he lives with his parents or with a roommate, then you don't want to make too much noise during sex. Even if he lives alone, you don't want to be so loud during the night that you wake up the neighbors. Even if you're both virgins, you should make sure to keep your laughter and the radio down. Don't give the neighbors a reason to complain.