Check your beneficiaries: Retirement accounts, like insurance contracts, require the assignment of beneficiaries. Check that your beneficiary assignments are current and correct—it's never pleasant when a grieving family member gets another sad surprise.
"You hear stories about wife No. 1 still being the beneficiary of a retirement plan, and that doesn't go over well with wife No. 2," said H. Jude Boudreaux, a certified financial planner at Upperline Financial Planning.
(Read more: Tips for year-end planning)
Such mistakes are common, said Brian Lampsa, vice president, investments at True North Retirement Partners of Raymond James.
"People just don't get around to changing their plan beneficiaries when they have a significant change in their life," he said.
Divorce, marriage, a birth, a death—all could require plan holders to update their beneficiary assignments.
Take the free money: Individuals can contribute up to $17,500 annually, tax-free, to a 401(k) plan. If you're over 50 years old, you also can add in another, so-called catch-up contribution of $5,500 per year.
Those amounts may not be realistic for most people, but a good way to increase your savings balance is to take advantage of any contribution-matching plan that your employer offers. A typical plan that might match 50 percent of contributions of up to 5 percent of income can be a huge boost to a retirement plan, even if investment returns are poor.
"At the bare minimum, people should max out the company match," Lampsa said. Even if the match is in company stock, it's still free money.
"There's no better place to get a good return," he added.
Rebalance your portfolio: Unless you have all your retirement assets in cash (and you shouldn't, advisors say), your investment portfolio needs to be regularly adjusted to maintain your desired level of risk.
For example, if you've settled on the classic allocation of 60 percent stocks and 40 percent bonds, you'll need to regularly rebalance the portfolio based on movements in the market. The run-up in equity prices and interest rates makes this particularly important this year.
(Read more: It's time to re-balance your portfolio)
"If you don't have an automatic rebalancing tool, it's smart to check your portfolio every three months," Boudreaux said.
Opt for an IRA rollover: If you've changed jobs this year, you have a decision to make about your 401(k) plan. You can cash it out, roll it into a personal IRA or roll it into another 401(k)—if you have a new employer who offers one.
Don't cash it out, advisors warn. You'll be liable for taxes on the full amount as well as penalties for withdrawing funds if you're under 59½ years old.
It might be simplest to keep your retirement funds all in one place, in a new 401(k) plan. But Boudreaux advises clients to put the assets into a personal IRA, because of the greater investment options available and a likely lower cost to the investor.
(Read more: Is your retirement plan on track?)
"We recommend people rollover their [401(k)] assets into their IRAs when they can because they're more flexible and it's easier to get your hands on the money if you really need it," he said.
Consider the Roth conversion: Ideally, investors should maintain multiple types of retirement accounts that they can use for a variety of objectives. This includes having a Roth IRA.
Contributions to a Roth IRA are not tax deductible; however, the capital gains on assets accumulate tax-free for beneficiaries. That makes it a good place to park growth-oriented assets. In a traditional IRA, the gains will ultimately be taxed as regular income when they're distributed. And, compared to traditional IRAs, Roth accounts also offer more flexibility about when and how you take distributions.
"We love Roth IRAs," Garrett said. "We want to see clients diversify their holdings and their accounts."
Garrett recommends that investors consider converting at least part of their traditional IRA holdings to a Roth plan. The big hurdle with such a conversion, however, is the upfront tax bill: Individuals are taxed on the entire amount at their prevailing tax rate. If you don't have excess cash on hand to pay the taxes, the conversion probably won't make sense.
Conversion to a Roth IRA is, however, particularly advantageous for people who've become self-employed or who have experienced a significant drop in income and, therefore, tax rates.
(Read more: When is the best time to open a Roth IRA?)
"Everybody's hung up on the tax bill, but it doesn't have to be all or nothing," Garrett said. "A life change may present a real opportunity; instead of converting the entire IRA, you can convert half the account or even just a bit of it."
—By Andrew Osterland, Special to CNBC.com.