1.
Always RSVP — even on Facebook.
2.
Don't assume you can bring a plus-one (or, like, plus-eight).
4.
Give a lil' gift to the host.
7.
Learn how to make one excellent drink.
8.
Keep a deck of cards in your bag, just in case.
11.
I'm sorry, but...mingle.
12.
And if you know that someone there is only friends with the host, make an effort to include them.
14.
Bring your own containers for leftovers.
15.
Don't overstay your welcome.
16.
Offer to help clean up.
17.
And don't leave without thanking the host.