Being a host is hard. But there are certain challenges in being the guest too.
For myself, I'm never comfortable in someone else's place. There's always some awkwardness. Where is the toilet paper kept, and are the towels on the towel bar strictly for decoration? What about meals? If you're the first up, do you start the coffee pot?
We've all played both roles at some point, and house rules change depending on the people you're staying with. But I do believe there are some universal courtesies a guest should observe.
1. Keep your space reasonably neat: making your bed, tucking dirty clothes into a corner of your suitcase, and so on. This is doubly important if your bed is in a public space, like a family room.
2. Always offer assistance—with meal prep, cleanup, or other mealtime tasks that arise. You'll likely be turned down, but you could be the hero.
3. Thank the host. Your length of stay will determine how often you show appreciation and your effusiveness.
4. If you're a relative, still follow these rules. Sure, your family has to have you back, but your name won't raise their blood pressure if you're a good guest.