Arrive with a present. Think beyond wine. One idea: "Balsamic vinegar that's been aged for 25 years and first-press Italian olive oil," says Dorothy McGivney, editor of jauntsetter.com. "Your friends will think of you every time they dress vegetables or pasta."
Dial down your phone. "Turn off the data connection," says Nick Bilton, tech columnist for The New York Times. This way you can get emergency calls but not distracting e-mails, texts, and tweets.
B.Y.O. Picky eaters should "offer to pick up some groceries," says cookbook author Katie Lee, including treats others will like. Chocolate is a no-brainer.
Keep it clean. "Respect the sink area in a shared bathroom," says Jolie Kerr, cleaning columnist for thehairpin.com. Rinse the basin, wipe the counter, and keep toiletries in a case or in your room.
Pick up a tab. Treat your host to a fancy meal. "I'll usually phone the restaurant in advance to let them know I'll be paying so a check is not presented," says Relais & Châteaux chef Barbara Lynch. "This avoids any 'fighting.'"
Have a backup plan. If you need to make an escape, use an app like Magic Tap's Fake Calls to feign a crisis. Some acting advice from GCB star Marison Nichols: "If it were a real emergency, you'd just go—so deliver the line, 'I've got to go' and get out of there."
Leave a lasting impression. "A hand-written note is a lovely footnote," says Beth Salvini, owner of New York's Greenwich Letterpress. Add a boxed set of DVDs or a cookbook your host will love—and perhaps you'll reap the benefits if they ask you back.