You can help by frequently cleaning up the room. Also, if you would like to use one of your roommate’s items, like a microwave, ask first. Finally, try and build a friendship with your roommate.
You should be respectful towards your roommate’s personal privacy and space.
You should communicate with your roommate and be respectful of each other.
I think your roommate should respect your space. They shouldn’t overstep their boundaries. You should communicate with them occasionally to see if anything is bothering them.
I have three things that I think are vitally important for being a good roommate which are 1) Respect your roommate’s privacy, 2) Keep your side of the room tidy and 3) Mind your business.