Depending on the cut of your dress, there are several types of bras you can go with on your big night.
Halter
Halter bra straps extend around your neck, rather than over your shoulders. They should slide under your dress and completely disappear.
Plunge
If your dress has a plunging neckline you are going to want support and push-up power. Be sure to try it on with your dress to avoid any view of cups.
Strapless
A strapless dress will require a strapless bra, one that gives support without shoulder straps. These may have some kind of adhesive to stay in place.
Backless
If your dress shows your naked back but you still desire the support of a bra, look to adhesive bra cups. These either adhere to your breasts or your sides to avoid lines.