The trick to getting your updo to look its best is to use several of these pins in different directions to hold your hair in place. Don't rely on too much hair gel as this just makes your hair stiff. You want your hair to be able to withstand the humidity, but also to be touchable by your date.
You want your curls to be loose. The looser and bigger the curls, the cuter you will look. First, pull your hair up, use some baby powder to add fullness and then tease your hair.
Other looks are more classic, like the French Twist. You have to slick back your hair with gel. Part it on the side and pull the hair down. You may need the help of a hair rat. No, not a real rat. You can get this at a beauty supply store. It will help you pull your hair down if you have real smooth hair. You will still need lots of long pins.
Starting with just straight hair, you can use large curlers to get those nice big curls. Once you have them, you can position them in place on top of your head, towards the back. You don't want your hairstyle to make your face look too long, unless you have a round face, and then it will help balance your geometry.
You can use shine serum to give you that sleek sophisticated look. Be sure to use plenty of pins, flexible hairspray, not the max hold kind, and gel if you need it.
Experimentation before prom will be the key. Use what works best for your hair. Find some pictures on the web; try it out with these ides using the pins, gel, and hairspray.