^ like the above post said, washing your hair less will hhelp to reduce oil. when you wash your hair too frequently, the shampoo starts to dry out your scalp. Then, your scalp, lacking moisture, does the only thing is can do. It makes oil.
A fantastic product for an oil scalp is Rene Furterer Complexe 5. It is a scalp treatment to be used once or twice a week. It is an oil, and it smells awful. I knwo i know, your thinking i need less oil. But this baby works. It works by applying 35 drops on the head, section the hair off into five and do five drops on each section. Massage the scalp. You will start to feel your scalp heat up a bit. This is because all the blood vessels are opening, and nourishing your scalp, and the root of your hair properly. It encourages them to be in optimal health. This product can help with things like; too much oil, not enough oil, hair loss, hair growing in limp, hair growing very slowly, dandruff. The idea is, if your in optimal health, these problems shoudl not exsist, or decrease dramatically.
Complexe 5 shoudl be used 10 minutes before you jump in the shower. Use a treatment based shampoo on top, like the Rene furterer Cubrabicia (i think?) line for oily scalps. When you use the complexe 5, for about 10 minutes, your scalp is open to recieve treatment products much better, so they work more effectivly. The complexe lasts a good 6 months. It smells awful, but gets washed away within 10 minutes, so who cares.
For myself the complexe made my hair grow quicker, and i noticed a lot less hair loss. I was loosing a normal amount of hair, but when i used it consistently, i would loose about 1/4 of what i used to loose. Our hair's life span is about 7 years or so. With complexe 5, your single hair's lifespan can increase by a year or two. so for girls with fine hair lacking volume, this will help.
My BF was dandruff prone, and that product cured him of it completely!
give it a try, im sure it will help you.