The most important tip for living within your means is to understand your cash flow. Before you set a financial goal, you should know how much money you make after taxes and understand your expenses. Some expenses are fixed, like rent/mortgage, car payments, and student loans, and others, like groceries and gas, can vary from week to week but may remain relatively steady over time. Even with fixed expenses, you can still find ways to lower them, such as getting a less-expensive apartment or finding a roommate to split the cost.