Set a date for the bills
Being a student is stressful. The last thing you need to worry about is when your friends will pay their share of the bills. Set a date and stick to it.
Agree to share or not to share
Set your boundaries for groceries or decide who can use which spaces at which times.
Organise who does the chores
No one loves a messy living space. Agree to who does what chores to keep your place how you like it.