My son is six and a half... Besides the basic rules (no hitting, no stealing, no lying... etc) our house rules are simple:
Hungry? Ask a grownup. Other than water, you need to check in. I might need that item for dinner.
Food/drink stays at the table. (Very occasionally we'll break that rule, but I put an old blanket over the couch first.)
Happy to show you the 'grown up' spaces of the house (bathroom cabinets, some other cupboards) if you ask, first.
Certain rooms and the outdoors are not 'free space'; Kiddo needs to ask before going into those spaces as they are not 'his'.
No playing IN the bed. When friends are over, doors stay open (except bathroom.) You may close your bedroom if you want privacy alone.
One person talking at a time. Nothing makes me nuttier than having people talk over each other.
We don't really have any issues with electronic devices at this point. If/when he has something remotely tempting to play with in the evenings, he'll hand it in 30 min. before bedtime.
Talking and asking questions is better than getting mad.
Use your manners and ask, don't tell, others what you are needing from them.
Ask before you start to use someone else's stuff. This means that adults must ask Kiddo if they want to use something that's specifically 'his', if only to model this.
Daily chores must happen for the day to progress. Homework and chores (completed and reviewed) come before tv/media time and playtime.
and no books in the bathroom. We only have one bathroom and three humans--- it can get busy!