1. Pay in cash as often as possible. People are more prone to over-spend on credit cards because they don't actually SEE the money. 2. Keep a spending journal. Write down every penny you spend on anything and everything. It'll help you see where you're wasting money and where you can save. 3. Set goals and rewards for yourself. For example, once you put $500 in your savings account, you can buy yourself a new pair of shoes. That kind of thing.
As a girl like you, I often make unnecessary spending. I think, the best way to control those habits is to keep yourself busy. And in the meantime, try to earn more money is an efficient way to help you.