You can't totally stop oily hair. However, if you are washing it too often you will overstimulate the oil glands and make it even oilier. So try to wean yourself off wahsing it every day. Also, use body boosting hair products - they seem to plump the hair up and make it appear less oily.

I have used a product called Shampowder. It's a hair powder. It totally works and i like the smell.

For a quick fix use talcum powder, make sure you don't put too much in and rub it in well so that you don't look grey!! I find applying a bit at a time, rubbing it in, brushing and straightening hair, then adding more if necessary if the best way to do it.