The best way to avoid debt is to create a budget and stick to it. You are unlikely to maintain complete control of your finances unless you are aware of where your money is going each month. So, if you want to stay out of debt, you should make a budget.
Fortunately, this is a simple task. All you have to do is figure out your average monthly income and then subtract your expenses. You can then classify your expenses as either essential or discretionary. Once you've allocated money for each category of spending, you'll realize you only have $200 per month for clothing, $400 for food, and so on.