This is some basic info about oily skin that might be of some help:
"Oily skin basics
Oily skin produces excessive amounts of sebum, a lipid-rich protective substance. A good thing about oily skin is that it is usually well-moisturized due to its own protective oil. The downside is that it may look shiny or dirty and tends to develop large pores and be prone to acne.
Oily skin routines usually include the following recommendations:
Wash your skin twice a day with a cleanser containing salicylic acid, a beta-hydroxy acid that reduces sebum production.
If you skin is extremely oily (e.g. oily even after basic cleansing), you can follow with alcohol-based toner with salicylic acid. Most people should avoid alcohol-based cleansers and toners due to the drying effect of alcohol. However, for extreme cases of oily skin, it may just do the trick.
Generally, people with oily skin shouldn't moisturize. If you feel you have to, apply nonocclusive, noncomedogenic, oil-free moisturizer after cleansing.
Use oil-free, noncomedogenic sunscreen whenever sun exposure is expected.
If the above steps are insufficient and you are still producing too much oil, try treatments that reduce sebum production. They include topical vitamin A creams (retinol, retinal or retinyl palmitate), sulfur creams, azeleic acid and retinoids (tretinoin, tazarotene, adapalene). Retinoids and high-strength sulfur creams require a prescription. If your oil problem is so bad that you are considering prescription treatments, you should probably see a dermatologist anyway.
Some people with oily skin may benefit from a clay/mud mask once a week."
From:Skin Care Basics
Don' make the mistake of doing anything drastic just before prom - start slowly well in advance so you know how it's going to react with your skin. And, it goes without saying: No tanning beds!!
I hope yu have a great time!!!