The long gown is a classic choice for a black-tie event, and is the best choice for the most formal of occasions, such as an evening gala or ball. Younger women should choose a fitted gown that flows elegantly and is made of a sophisticated fabric, such as silk chiffon or silk jersey. Older women might prefer a gown with a structured full skirt of taffeta or crepe, which can be very flattering. It's acceptable to bare your shoulders, but add a cropped jacket or shawl for chilly moments.

A cocktail dress -- a short or mid-length dress traditionally worn for early evening events, such as a pre-dinner cocktail hour -- is appropriate for most black-tie events. It must be dressy and knee-length or lower, so as not to be too revealing. The best occasion for a cocktail dress is an early evening black-tie wedding, or an event that will involve lots of dancing. Choose a dress made of special fabrics like taffeta, satin or lace with festive but formal touches such as beading and sequins.

It's now acceptable to wear dressy evening separates, such as blouse and skirt or a jacket and palazzo pants, to a black-tie event. As you would with a dress or gown, choose separates made of luxurious fabrics such as silk in well-fitting, flowing shapes. You'll create a formal outfit wearing a knee-length A-line skirt with a festive print and beaded silk blouse, or flowing silk palazzo pants and a textured jacket or sequined bolero with jeweled buttons over a silk blouse.

In addition to luxe fabrics, accessories can help a black or monochromatic ensemble look dressier. Jewelry dresses up an outfit, so try a statement necklace, cuff or chandelier earrings with a solid-colored dress or gown. If your skirt or dress is short, eye-catching shoes, such as a pair of jeweled pumps, help to make it more festive. The evening bag or clutch is also a integral part of a black-tie ensemble. If your outfit is basic, try a bejeweled, sequined or metallic clutch for added shine.