Don't be a space hog.
Empty a few cabinets and drawers so your houseguests have somewhere to unpack their things.
Do leave a warm welcome.
Wine does the trick, but why not get creative? You could prep a home-cooked meal your guests can heat up. They'll be grateful—and more inclined to treat your house with care.
Don't raid the liquor cabinet.
Dipping into your host's salt or ketchup is fine, as long as you don't finish it. With anything else (toilet paper, bread, olive oil), buy or BYO.
Do swap more than just the house.
Exchanging cars is convenient—and saves what you'd spend on a rental. And some swaps even include pets!