The Outfit
Know what you want to emphasize about your shape - select clothes (and undergarments) that present the look and shape you want. Your hair plays a role in defining your shape! Hair should be compatible with/balanced and aligned with the shape of the outfit.
Black dresses/gowns can look sleek, but some women need to include colors (scarf, jewelry, other accessories) so that they don't look too pale when in black. Also consider other dress/gown colors that may be a better match with your skin tone, eye color and hair color, while delivering the dramatic look you want.