If you're petite
(5'3 and under)

You will look good in:
Column-like sheath or A-line dress. These shapes create a long uninterrupted line. Stick to open necklines like strapless which is usually cut straight across, but it can also peak on the sides or have a slight dip in the center. Another neckline that would look good on you is off-the-shoulder, which sits below the shoulders, with sleeve-like straps that cover part of upper arm.
Stay away from:
Ball gowns and dresses with voluminous fabric, as they might look like they're wearing you.

If you have a rectangle shape
(shoulders and hips are the same width)

You will look good in:
Empire-waist gowns and ball gown with a basque waist will give you the nipped-in look you crave.
Stay away from:
Sheaths and dropped waists, which will make you look even boxier.

If you're an hourglass shape
(shoulders and hips are the same size and waist is about 10 inches smaller then hips)

You will look good in:
A ball gown with a basque waist, which has a slimming effect. A high-waist A-line with low neckline also flatters curves.
Stay away from:
A slim sheath or slinky bias cut which will cling and may add extra inches.

If you're busty

You will look good in:
Uplifting foundation garment and an off-the-shoulder bodice. You can curtail your curves with a one-piece minimizer worn under a gown that boasts a fitted bodice to emphasize your waist. A full skirt will balance everything.
Stay away from:
Overdoing the bareness will take away the focus from your face.

If you're pear-shaped
(shoulders are very narrow, waist is little larger and hips are the widest part)

You will look good in:
Strapless ball gown which will cover your bottom and focus on you're better half. Off-the-shoulder neckline will make your top look more in proportion to your bottom.
Stay away from:
A sheath which can be very unflattering. V-neck which neckline dips down in the front in a flattering V shape will draw the eyes downward, where you don't want them to go.

If you have broad shoulders

You will look good in:
A halter top which features straps that wrap around the neck. Or a gown with long off-the-shoulder sleeves. Select a dress with a narrow bodice that offsets you shoulders and helps create an hourglass shape.
Stay away from:
Trying to conceal your shoulders-it sometimes produces the opposite effect. IF YOU'RE TALL You will look good in: Everything from sheaths (if you're also slim) to A-lines and ball gowns. You can accentuate your collarbone with a fitted bodice and an open neckline like strapless, off-the-shoulder, and sweetheart. Stay away from: High necklines and long sleeves. Also updos and headpieces will add too much extra height.

If you're slim

You will look good in:
Ball gown will make you look like a beautiful ballerina. It's very feminine shape that will balance out your overall silhouette. A gown with a very low back will also look good.
Stay away from:
Off-the-shoulder which sits below the shoulders, with sleeve-like straps that cover part of upper arm. Halter top features straps that wrap around the neck, or a high neck with deep armholes, we would recommend staying away from that too. And if you're also flat-chested, avoid a darted bodice made of stiff fabric.