6. Assume if your 401(k) is fully funded, you're done.
Putting money into a 401(k) is a good start, but it's also important to consider other investment vehicles beyond your employer sponsored plan. A good next step is to put money into a Roth IRA, another retirement-savings vehicle that offers tax benefits and is particularly well suited to younger people who earn less than the income cap — $116,000 a year or less for individuals, $183,000 or less for married couples filing jointly. The maximum yearly contribution for both accounts in 2015 is $5,500 (or $6,500 for people age 50 or older).
Contributions to this type of fund are taxed when they're made, so you can withdraw the contributions and earnings tax-free once you reach 59 1/2.
If you've maxed out your retirement plans, an end-of-year bonus is also a good opportunity to start investing in low-cost index funds, which legendary investors Warren Buffett and Jack Bogle recommend, or to consider online investment platforms known as "robo-advisers," which manage your investments for you through unique algorithms.
Of course, you'll want to make sure 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, the quicker you put your money to work and jump start its growth, the better.