I have a quick gripe. I'll just do it and then I can move on. There is a very big difference between a costume party and a character party. Nobody throws Halloween character parties and there's good reason for that. So if your costume involves your voice or the way you walk or certain choreographed dance moves, it's not a costume. It's an impersonation. And it's probably not a good one.
What not to do:
My older brother decided one year to dress as an old man with a walker. And instead of just looking like a senile old man, he acted like one. So he yelled at people about bowel movements and talked about the old days... for 4 hours. He didn't once break character. Which was funny for about 14 seconds... out of the 4 hours.
What to do:
One of my younger sisters dressed up like Where's Waldo. Just a simple striped outfit and matching hat with some thick glasses. Then she stood in the background of every picture she could get into. Hilarious. Not over the top. No voices, actions, etc. Just looking like what she was supposed to look and adding a little humor for pictures. Great costume.
So if you're coming to any of my future Halloween parties, don't act like something, just dress like something.