You know the saying, "Bad habits are hard to break." But sometimes it's even harder to create good habits, especially good money habits. Here are five essential money habits that you should master by your 30s:

Create and stick to a budget

Don't view budgeting like balancing a checkbook, simply tracking where you spend your money. Rather, your budget should tell you how much money is going toward mandatory expenses — rent and student loan payments — and how much you have left over to save or spend.

Free apps like Mint and Mvelopes make it easy.

Live below your means

More than 20 percent of millennials spend more than they earn. Even if you're scraping by paycheck to paycheck, you're still falling behind on retirement savings. You have to make sacrifices — like skimping out on daily Starbucks runs and cutting down on weekend drinking. Reconsider where you eat and how much you're spending each meal. Small purchases can add up.

Manage credit wisely

Millennials are more likely than other generations to carry a balance, make minimum monthly payments and pay late fees. This behavior can harm your credit score and cost you money later. You can boost your credit score and improve your credit history by keeping balances low and avoiding opening too many credit accounts at once.

Build an emergency fund

Without an emergency fund, you'll likely have to rely on credit cards to cover a car repair, a trip to the emergency room and other unexpected expenses. Set up small, automatic deposits from your checking to your savings account. Even saving $25 every two weeks can save you $650 over the course of a year.

Save for retirement

Twenty-nine percent of millennials said they are actively saving for retirement. While saving for retirement might not seem like a priority in the face of student loans, the sooner you start, the more quickly you can build up savings — that's the power of compound interest.