A Black Tie invitation calls for formal attire. Men should wear tuxedos; women should wear cocktail, long dresses or dressy evening separates.
This is not to be confused with Cocktail Attire, which means short, elegant dresses for women and dark suits for men.
These are not the only options for parties- there are Black Tip Optional affairs, Semi-Formal events, Creative Black Tie parties, etc. I would like to highlight a few differences for you and incorporate a couple of rules to live by.
1. Black Tie means it's fancy.
You cannot get around this in any way. If you don't want to dress this formally, don't go the event.
Your best color choices are black, navy, gray, deep jewel tones, or red. Pastels are not ok, and bland colors like oatmeal and cream are inadvisable.
2. Cocktail means it's fancy, too, it just means men won't be in tuxedos and you don't have to wear a ball gown. Dresses are still your best option.
Look, if you prefer separates, that's cool, but they must rise to the same level of formality that you'd have in a fancy dress.
Tuxedo pants and a jewel-toned blouse could be fun, or a silk skirt with a sequined top would be a good option.
3. Velvet pants are not ok.
Don't even CONSIDER them. I have said it before and I will say it again: they always look cheap, no matter what you paid. Why would you do that to yourself?
4. Red and green together are not "festive." They are tacky.
5. This is an office affair, whether you are bff with half the office or not, so don't get cute.
Dress in keeping with the level of formality of the event and now is not the time to reveal the peircing/tattoo that you've been keeping under wraps.
6. Notice how in each of the above descriptions of black tie and cocktail did not include any mention of sex? That's because they do not call for over sexiness.
Dresses are fantastic, but keep them mid-thigh at the SHORTEST (and even then, with tights and lover-heeled shoes) and do not show massive amounts of cleavage .
7. Chose under garments carefully.
Bra straps hidden; no visible panty line; control top controlling, not rolling, so you have to yank on it every 5 minutes.