Veneers. You can get veneers, which are thin shells that are custom made out of tooth-colored material and placed over your teeth. A veneer placed on top of your teeth can easily and greatly improve an imperfect smile.
Whiting. Teeth whiting would be the first thing to try. Basically the dentist will inset a tray filled with concentrated hydrogen peroxide under a high intensity light the entire mouth takes about an hour. If this doesn't work you could try making them bigger by placing veneers on your teeth....These are porcelianchips shaped like teth that are very thin and will bond to your teeth talk to your dentist.
Crown Lengthening. If your teeth appear "small", then a recontouring of the gum tissue around the teeth can give them a "longer" appearance. If you have spaces between your teeth and the teeth themselves are small, then veneers may be the answer. Consult with your dentist for your specific situation.