I haven’t had a roommate for a couple decades, but these are two danger zones.
Chores: Agree to a fair distribution, set a schedule and stick to it. We had 4 roommates and 4 main chores. We agreed to do them on the same day and it worked well.
If one of you is neater than the other, deal with it now. If one of you is louder and/or stays up late, talk about those things. If you don’t, the louder messier roommate will do what they want and the quieter neater person will seethe and fill with rage.
Food! What’s shared and what’s personal?
You’re best friends so you’ll get along great, just try to be proactive when dealing with any strife.