This is probably one of hardest and fastest rules in personal finance. It’s so obvious that it shouldn’t even be said over and over and over again. Still, not everyone follows this.

Many people are still living in a paycheck to paycheck lifestyle. Some are even doing worse, sinking in even more debt every month. Here are some tips to help you spend less than what you earn.

1. Review your monthly cash flow. Take note of what you earn. Check all of your expenses. One great practice is to keep your paycheck. Balance your checkbook as well to see how much money you do have. Keep all of your receipts and billing statements.

2. Trim down all unnecessary expenses. Eating out for lunch and dinner might be costing you money. How much time do you spend at home? That cable bill might just be costing you money.

3. Put away 10% of your income as savings immediately. Pay yourself first every month. Money not in your pocket or wallet is often safe from being spent unnecessarily.

4. Try to be debt-free as soon as possible. Credit card interest is an unnecessary expense. Pay what you owe as soon as possible. Keep only one credit card.