Don’t expect the household to revolve around you. Vegetarians don’t need to swallow a hamburger with a smile, but they shouldn’t expect their hostess to stop eating meat. If you have anxieties do not bother your hostess or her guests about them, over and over and over. Do not expect your hostess to provide parades or banners or parties. A good hostess will greet you with open arms, settle you in and then take care of her other guests, staff and plans. She will not drool on your husband. She has a lot on her mind.
Don’t invite visitors without asking. While some hostesses are OK with you having a friend, it is wise and gracious to clear it with them first. This is especially true if you are planning on a group of French speaking Italians, or anyone at odd hours who is dressed as a pirate. It is always unacceptable to wake up the other house guests in the middle of the night.
Being a good houseguest means being good company, be good company. Withhold complaints and get into the swing of things, be it vibrant dinner conversation or adventurous activities. A fun time for guest and hostess alike is why you're there in the first place, and it's what will get you invited back. A good houseguest wakes up hung over in the morning and gossips with her hostess about the previous night’s activities by the pool.
Lastly, always remember that you’re a guest: Remember to be gracious -- after all, she is letting you stay in her rented home. Let your hostess know that you appreciate her kindness. It is usually considerate to reciprocate an invitation but in this case don’t bother. I’m busy.
*Thanks in part to Elinor Ames' Book of Etiquette (1939) and a bunch of other stuff.