(MONEY Magazine) – What's better than learning from your own mistakes? Learning from someone else's. You get the gain without the pain. This month's column will give you that chance--specifically, the opportunity to improve your own retirement prospects by applying lessons from today's retirees.

In two surveys conducted within the past year, Fidelity Investments and Putnam Investments asked recent retirees what they wished they had done differently. Now I wouldn't say the answers represent blindingly new revelations. But even if the responses aren't a total surprise, the fact that these people have the benefit of 20/20 hindsight makes their insights all the more compelling. Here are four lessons I drew up based on those regrets.

Lesson 1 LOOK BEYOND THE 401(K) Those of us still on this side of the retirement divide know we ought to be putting the maximum in company plans like 401(k)s. But what we may not appreciate is that a 401(k) alone probably won't be sufficient. Few of us get started early enough or stick with it our entire career. So to make up for when you failed to contribute--or worse, spent your 401(k) money rather than rolling it over when you switched jobs--you've got to sock away more money outside your plan. Clearly a traditional or Roth IRA is the first place to look. But there are other options that offer long-term growth and tax advantages. Tax-managed funds, for example, employ investing strategies that can shelter a good portion of your gains until you sell your shares.

Lesson 2 DON'T LET YOUR LIFESTYLE OUTPACE YOUR INCOME Christine Fahlund, a senior financial planner with T. Rowe Price, says one of the biggest obstacles to saving for retirement is our tendency to "accelerate our lifestyle." Rather than save more money as our income rises, we're too quick to plow extra dough into a more magnificent house, a fancier car or whatever. This may be sustainable while you're racking up raises. But once the paychecks stop, it's difficult to maintain a grand lifestyle. So when you're five to 10 years from retiring, bank your pay increases. You may even want to consider ratcheting down your lifestyle, both to free up cash to invest and to reduce the chance of having to endure a sudden severe cutback after you retire.

Lesson 3 KNOW HOW YOU'LL REPLACE YOUR PAYCHECK Most of us retire with no real system for turning our savings into income. What's worse, Fidelity's survey found that even though many retirees regretted not having paid more attention to income, 51% said they still didn't know which assets to tap first.

That's unfortunate because you may run out of money--or live too parsimoniously--if you wing it. Before you retire, plan how you'll create a "paycheck" from Social Security, your assets and other resources. You can download a budget worksheet from the "Turning Savings into Retirement Income" area in the Retirement Countdown section of the TIAA-CREF website (tiaa-cref.org). Use T. Rowe Price's retirement income calculator (www3.troweprice.com/ric/RIC) to see how long your money might last.

Lesson 4 DON'T BE TOO QUICK TO LEAVE WORK Nearly four in 10 workers say they want to retire before age 65, according to the Employee Benefit Research Institute. Granted, the decision to leave isn't always voluntary. But if you can manage it, staying even a few extra years can dramatically improve your finances. Says EBRI president Dallas Salisbury: "If you have a job with a retirement plan and health insurance the employer pays at least part of and you're not miserable, the longer you stay the better off you are." And the more comfortable your retirement will be.