Well if you're going to wear a mask, you might not need to focus much on eye makeup. Even so, you may still apply mascara or even a neutral-toned eyeshadow. A shimmery champagne or a bronze color would be really pretty when if catches the light momentarily.
I'd say that the skin and lips are the most important parts of the look though. Try to achieve a really natural, glowing, "lit-from-within" effect. That'll depend on your skin type though. If you have good skin, you could get away with a tinted moisturizer (no SPF though, to avoid looking unusually pale in pictures!!!) and some lightweight concealer. For concealer, I like MAC Select Moisturecover
For cheeks and lips, try a fresh peachy-pink color. Or you can go for a more dramatic lip color. Just keep in mind that you might eat and drink and the lipstick might come off anyway. It's up to you if you wanna reapply.
I hope you have fun at prom! Gorgeous dress BTW