Let's start with the bad news: 401(k) contribution limits won't rise in 2011, for the second year in a row. Fortunately, the existing limit is nothing to sneeze at.

For 2010 and 2011, the maximum contribution to a 401(k) (or similar investment account) is $16,500. If you're 50 or older, you're permitted an additional "catch-up" sum, bringing the total to $22,000. (The limits for IRA contributions remain at $5,000 -- and $6,000 for those 50 and up.)

Max it out
A conventional rule of thumb in financial planning has been to save and invest 10% of your income each year. That's a nice round number, but it's way too low for the many people whose current nest eggs are far smaller than they should be. Saving 15% will serve you better, and if you can save even more, your future retired self will thank you.

If you're feeling particularly bold, try to contribute the maximum amount. You don't necessarily have to do so in every remaining year of your working life, but try to do so now, and for a while. The dollars you invest early in your career can grow the most, because they have the most time to do so.

Most Americans have saved much less than they'll need to ensure a comfortable retirement. You can improve your golden years in a big way by saving and investing as much as you can today. Between a 401(k) and an IRA, you can put aside a nice chunk of money toward your golden years.

Lighten your tax bill
There's an additional benefit to making big retirement contributions: Tax savings. Money plunked into a traditional IRA or 401(k) is deducted from your taxable income, so you don't have to pay tax on it. So saving for retirement doesn't just help you in the future -- it can also save you thousands in taxes this year.

You do get taxed in retirement, though, when you withdraw funds from these accounts. But you may be in a lower tax bracket then, which can be an extra benefit. (Roth IRAs work differently, but can be even more powerful. You invest post-tax money, but get to withdraw your money tax-free.)

The lesson here? Aim high. Big contributions will yield big benefits -- and the sooner you invest, the better.

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Longtime Fool contributor Selena Maranjian does not own shares of any companies mentioned in this article. The Motley Fool is Fools writing for Fools.