I'm going to be really boring here and suggest you wear something comfortable!
Personally, I don't bother dressing up for clubs, and I hang around with people who don't bother, either. On the rare occasions that I do dress up to go to a club, it's usually just a fitted black buttoned shirt, black skinny jeans and heels, or a little black dress if I think I'll get hot.
The reason I don't buy clubbing dresses is because, for girls, the clubbing "dress code" is usually pretty trashy. It's amazing how many people in clubs look exactly the same—all wearing whatever style dress is currently in season, whether it's flattering on them or not, and enormous heels.
I don't really see the point in making such an effort just to look like everybody else.
Deciding What To Wear
Obviously, you want to look good, but that doesn't mean you have to wear jeans (although there's nothing wrong with that). Here's how I'd decide what to wear:
- Ignore what's currently in fashion, and instead, work out what looks good on you. I bought a black lacy skater dress from ASOS a few months ago, and although it looked gorgeous in the picture and it was the right size, it completely hid my waist. It always seems unfair when a style you like doesn't look good on you, but you have to accept it, unfortunately! If you feel confident, you'll look confident.
- Wear something that won't need adjusting every five seconds. If you're dancing and drinking, the last thing you want is to be checking your boobs haven't fallen out.
- Don't wear anything too expensive, unless it's a really nice club. You'd have to be very brave to wear something white, too—nine times out of ten, you end up getting drink spilt on you in a club, and if it's hot and crowded, you'll probably be covered in other people's sweat as well as your own.
- Wear something that makes you feel good about yourself. I always enjoy myself more if I'm happy with how I look.
- Clubbing dresses are usually short. However, if you're wearing something that's very revealing up top, you might want to go with a slightly longer skirt—just above the knee, for example. Or you could do the reverse, and have a modest neckline or collar and a shorter skirt.
- Wearing tights is usually a good idea, even if they're really thin and skin-coloured. They make a huge difference when you're waiting outside for a taxi, and they make your skin look smoother.
Footwear
I know you asked about dresses, but I think it's also worth thinking about shoes. If you've got a pair that look gorgeous but are really painful, get gel pads (like Party Feet) for the balls of your feet. Tights come in handy here, too—shoes hurt a lot less when your skin isn't rubbing directly against them!If you're wearing a really striking dress, you can even get away with wearing flats. Last summer I just wore Toms when I went clubbing, which was comfortable and stopped me tripping myself up!
Ask Your Friends
It might be an idea to ask your friends to help you decide on a dress, if they know what sort of club it is. You can also make sure you're all dressed to the same "level"—as in, nobody feeling awkward because they're the most dressed up, or wearing the most revealing dress!
Ultimately, you want something that'll look good, make you feel good about yourself, and be comfortable enough to allow you to enjoy your night. Have fun!