Change is extremely difficult for some, and adjusting can take a bit of time — especially if you're adjusting to living with someone you've never met before.
A person's freshman year roommate can sometimes make or break their college experience. However, by establishing a good relationship with your roommate, it could make the transition to college go a lot more smoothly.
Set rules and boundaries
Right off the bat, discuss anything you feel is important, like: how you both feel about having guests, what your sleep schedules are like, whether or not you want to share your food, etc.
Set a cleaning schedule...
… And POST IT IN YOUR ROOM/BATHROOM. This will make it so much easier for little chores to get done before things get too messy.
Respect their space
Don't put your things on their desk, you have your own for a reason.
Ask before you borrow
More times than not, they'll say yes — as long as you put things back in the right places.
Make other friends
It's great if you and your roomie become quick friends, but don't cling to them. You both need time away from each other, especially since you'll be sharing a room for the rest of the school year.
And if you aren't friends...treat them like one anyway
Invite them to grab coffee with you every once in a while and ask them how their day was. It shows you care and eases any tension you two might have.
Ask them periodically if they have any concerns
Even if your roommate never complains about anything, they could still have problems they are just too hesitant to address. By you asking if they have any concerns, it'll make the confrontation a lot easier.