Go monochromatic or tonal. Although women have long turned to all black as a no-brainer for dressing slimmer, you can also use other hues to create a longer line like different hues of the same color family: charcoal, silver and heather gray for example.
Choose one strong vertical element. An unbuttoned jacket or vest can give you that strong vertical line that keeps the eye moving up and down, rather than across.
The sheath dress is the perfect dress silhouette to create a strong vertical line.
Slim pants worn with a tunic top, a long scarf wrapped around your neck with ends left dangling and layers of long necklaces all create a strong vertical presence as well.
Even going with vertical seaming or prints can add to the eye traveling up and down rather than across.
Wear heels.
The best way to visually increase your height is to physically increase your height.
Even a slight heel (two inches or so) will improve the line of most outfits and give you a longer look.
If you can wear really high heels, they are still the best way to look taller.
Try nude shoes.
Hollywood’s trick to having endless gams is to wear nude shoes with bare (or seemingly bare) legs.
Nude shoes look great with just about any color and you can even cheat to wear them with super sheer nude hose or nude-colored fishnets.
Red and black dresses look fresh and new when paired with nude shoes.
Add a V-neck top.
The V-neck top adds visual height and elongates the neck.
Even if you wear it layered (like a deep V-neck sweater with a tee layered under it) it will still give you a longer line than either a crew or boatneck top would.
The deeper the V, the greater the illusion of height.