There's a nerve that splits between your third and fourth toes that causes pain when pressure is put on it. To relieve some of that stress on your poor little toes, tape your third and fourth toes together (your big toe is #1) with some medical tape or a band aid. Obviously, this trick only works with closed-toed shoes where your third and fourth toes aren't exposed.
Deodorant: According to Mashable, rubbing some deodorant on the back and sides of your feet can make new heels feel smooth as your armpits! The deodorant "eases the friction" between your skin and tough new material to prevent blisters. Speaking from experience, the most important thing here is to make sure the deodorant is dry before putting your shoes on.
(All of these products can be purchased at a drugstore or any store specializing in dance.) Often, when I’m wearing heels the pressure on the balls of my feet is too much to handle and I get a horrible burning sensation if I walk in them for too long. Well problem solved, I just take a piece of Gel Moleskin and stick it to the bottom of my foot completely eliminating the friction!
The problem with buying new heels just for prom is that since you bought them just for prom, you don't want to get them dirty before the big night, so you never properly wear them in. Heels already do a number on your feet, but if you wear them to prom right out of the box, you risk getting blisters and cramps and having to ditch them way before the night is through because of how badly they hurt your feet.