9. Bring a small gift. 
This is something I generally neglect to do, then kick myself afterwards for having forgotten, yet again, to bring my host just a little something to say thanks. Nobody invites a guest expecting to receive something in return, but a thoughtful little gift is a very nice gesture nonetheless. Unless you’ve got a good sense of your friend’s decorating tastes, I’d stick with food and drink. A good bottle of wine, a gourmet jam from your hometown, those cookies from the bakery your friend loved so much on his/her last visit to your place … just make sure that it’s something special. As the cliché goes, it's the thought that counts, so if you're not going to put a little bit of effort into the gift, it's best not to bother at all. 

10. Write a thank-you note. 
Admittedly, I never, ever think do this, but on the rare occasions when guests have sent me a thank you, I’ve always been impressed. If you’ve taken any photos during your visit, make reprints and pop them into the envelope as well. The note and pictures are sure to remind your friend of just how much fun it was to have you visit – thus ensuring many happy returns for you in the future.