First of all,of course you should skip the veil on your head which is a basic start for not looking like a bride in a white evening gown. There are also a few other tips can help you look like :
Pick a dress more stylish and casual.Traditional Ball gowns have long been the traditional bridal look with layers.So to look more occasional,hunting for a different style that look more stylish with unique shape. Short, cocktail dresses can work, as can sheath dresses with dazzling beads, embellishments and peekaboo cutouts. Asymmetrical cuts on the bodice and skirt can also keep you far from the traditional princess bride appearance.
JSLD0092 from Jueshegowns.com
Use white as a backdrop, but not as the end-all. White prom gowns don’t have to be all-white.You can add a black or colored lace peplum skirt on bodice like the following one to create a fashionable look .Such overlays make a eye-catching statement on white and take you one step farther from the bridal look.It can be a great choice for any season, and these tips make it work for any elegant or formal occasion!