13 things to accomplish with your money before 40

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Everyone's allowed a few life mulligans, but by the time you've hit the big 3-0, you should have sorted out most of the reckless habits we tend to fall into as young 20-somethings.

This is especially true for money matters, considering you're close to entering your peak earning years. According to Payscale, college-educated men's earnings peak at an average age of 48 and women's earnings peak at 39.

To prepare for your peak earning years, here are 13 milestones to aim to achieve before hitting 40:

Contribute at least 10% of your income to a retirement account

You should already be contributing to your employer's 401(k) retirement account, and your 30s are a time to increase that contribution.

Many experts recommend putting aside at least 10% of your income. That may not be possible when you're first starting out your career, but it's a good goal to have by 40.

To work your way up to 10% of more, get in the habit of upping your contribution on a consistent basis — either every six months, at the end of each year, or whenever you get a pay raise.

Invest in something other than your retirement-savings plan

Many experts recommend using investment vehicles in addition to your employer's retirement plan to ensure that you'll have enough to fund your golden years.

If you're maxing out your 401(k) plan, consider contributing money to a Roth IRA or traditional IRA, research low-cost index funds — which Warren Buffett recommends — and look into the online-investment platforms known as "robo-advisers."

Of course, you'll want to make sure that your general finances are in order before you invest. But if you have a sound emergency fund, have prepared for future expenses, and are debt-free, then the quicker you put your money to work and jump start its growth, the better.

Establish savings goals and start setting aside money for big purchases

There are bound to be big expenses in your 30s — student debt, vacations, and kids, to name a few — that require diligent saving.

The best way to prepare for these expenses is to create savings goals, and then set aside money as early as possible. You'll want to adjust your budget so you can contribute a specific amount of money (depending on your upcoming purchases and time horizon) into a savings account each month. Treat this money like a fixed cost, meaning you must set it aside like you would do for rent or utilities.

Pro tip: Set up automatic transfers from your checking account to your savings accounts so you never even see this money and learn to live without it.