Dress in long pants and a shirt. Wear a leather belt if your pants have belt gaps. Tuck your shirt in if you want to seem neat and tidy. Not a T-shirt or tank top, but a shirt with a collar. Try to find a button-up long-sleeved formal shirt. It should have some kind of pattern or design on it. This will make you look more professional when you arrive at the party. If you want to be able to dance all night, then bring something comfortable to wear under your dress or jacket. Black-tie events usually mean business suits, so don't worry about looking too casual. Halloween is known for its costumes, so if you plan to go as a character from a movie or book, then check out some popular titles this year to choose from. There's no need to spend a lot of money on a costume; there are free ideas online that will help you create your own unique look. Wear clothes that you feel good in, that make you smile, and that fit well. You only get one chance to make a first impression so put some effort into choosing appropriate attire for a party event. Have fun!