You should start saving and investing for retirement as early as possible because it’s hard to make up for lost time.

Put your savings on autopilot by setting up automatic payroll deductions for your retirement fund. Many employers offer a 50% match of every dollar you contribute up to about 6% of your salary. Grab the free money by making the maximum contribution.

Read as much as you can about investment strategies for retirement. Check out the wonders of the Roth IRA and you may want to consider Exchange Traded Funds as an alternative to mutual funds for at least part of your retirement money.

In general, the younger you are, the more aggressive your retirement investments can be because you have more time to make up ground lost in a market dip. As you age, plan to move into more conservative investments such as bonds and CDs because you want to preserve your nest egg and have less time to make up losses.

You can no longer depend on Social Security or a company pension for a secure retirement. Yet a survey by TransAmerica found that 61% of respondents plan to rely on Social Security as their primary source of retirement income. This ignores U.S. Treasury Secretary Henry Paulson’s comment that Social Security as now funded is “financially unsustainable.”

The result: those who don’t save and invest for retirement need to cultivate a taste for dog food and ketchup later in life.

Here are five things you need to know about saving and investing for retirement in your 20s, 30s, 40s and 50s:

Investing in your 20s:

1. Draft A Plan – Your friends may vote you The World’s Frumpiest Future Fuddy-Duddy, but develop a retirement plan and put it in writing. Determine your goals and chart a course to achieve them. Your plan will change over time and as you gain more experience, but remember this bit of folk wisdom: if you don’t start, you won’t get going.

2. Squirrel Money Away – Think about saving 10% of your gross pay each month. Take it off the top. If you try to save what’s left over at the end of the month, you’ll quickly discover that expenses rise to consume available income. Stupid-proof your retirement contributions by setting up an automatic payroll deduction.

3. Stay The Course – Your savings plan is worthless unless you stick to it. You can’t use money set aside for retirement to take a dream vacation or buy a spiffy car. Don’t borrow against your retirement. Continue to read about saving and investing to achieve your goals. You’ll discover that the more you read, the easier it is to learn more – and the more you know, the better investment decisions you’ll make about your future.

4. Thick Between The Pockets – Those jeans you wore during your wild and misspent days as an undergraduate are likely to feel a little tight in your late 20s. Your task: keep your burgeoning gut under control and watch your spending like you track your diet. Make regular payments on your student loans and don’t run up huge credit-card debt. Both will help build a strong credit history. Pay your balance in full each month.

5. Uncle Sam Isn’t Your Brother – Social Security was created in the 1930s and the world has changed since then, a fact many politicians seem to overlook or willfully ignore. The Baby Boomers, now approaching geezerhood, will break Social Security as it now exists. Keeping the system alive will require a mix of higher taxes (on you) and reduced benefits for the flabby flower children. This means you can’t depend on government programs to secure your retirement.

Investing In Your 30s:  

1. Retirement vs. Kids’ College – Can’t remember where those kids came from, eh? Think! Don’t repeat the mistake many young parents make by putting their children’s college education ahead of their retirement. Your kids can work at school and there are scholarships and loans available to help with tuition and living expenses. Try this thought experiment: you walk into a bank and announce, “I’m here to borrow $500,000 for my retirement.”

2. But Don’t Forget the Kids – Money earmarked for your kids’ college education should come from what you have left after routine household expenses, savings and your retirement contribution. Remember: pay yourself first. Study 529 Plans but don’t jump out the window after calculating that you’ll need $750,000 or some impossible sum to get your kids through private universities. It’s never too early to tell your kids that they’ll make it through college on a mix of savings, scholarships, loans and part-time work.

3. Increase your retirement contributions – Your career is taking off. That means more responsibility and a fatter pay check. Consider boosting your retirement contribution to 12% or even 15% of your gross pay from your initial 10% or less. Take the money off the top and don’t worry about the kids.

4. Compile Financial Records – The importance of financial planning increases as you grow older. You need accurate records to see where you’ve been and to make good decisions about the future. Please note: tossing receipts and earnings statements in shopping bags doesn’t cut it as a filing system.

5. Your Portfolio Gets Whacked – If you get caught in a market downturn and your retirement portfolio takes a hit, don’t tear out your hair because you have ample time to make up your losses and build for the future. A downturn underscores the importance of being diversified. If you had all your eggs in one basket, this is a good time to learn about diversification.

Investing In Your 40s:

1. That Odd Sound – It’s probably struck you by now that you’re not immortal and that odd sound is time whistling in your ears. Looking ahead, you can see the soft outlines of middle age. Fret not, if you launched your retirement plan in you’re 20s, you’re in good shape. If you haven’t started planning for retirement, it’s time to get busy.

2. Increase Your Allocation – Your salary continues to grow and you should increase the amount you set aside each month for retirement. Your portfolio is no longer a back-of-the-envelope enterprise and it’s time to get a financial advisor. Consider fee-only services to be sure your adviser isn’t pushing something because it comes with a fat commission.

3. Review Plans – You may have plucked the initial numbers in your retirement plan out of the air. Now that you’re an experienced investor, it’s time to revise your plan and make adjustments as needed. Sit down with your adviser and review your portfolio. What are your successes? Failures? What could you do better?

4. Beware the BMW – Sure, sure, you’re successful and you’ve got the gut to prove it. A BMW, Mercedes or Lexus might impress the neighbors, but remember that a car’s value only declines. Don’t let the raiment of success ruin your retirement planning.

5. Duh and Double Duh – You haven’t started planning for retirement let alone set any money aside? Brilliant! Keeping mind that saving and investing for the future won’t get any easier with age. If you’re just starting, think about setting aside as much as possible because you’re playing catch-up. You need to develop a plan with a financial adviser. You may want to be aggressive, but don’t take on more risk than you can handle.

Investing In Your 50s:

1. Check the Calendar – If you’re not concerned, you’re unconscious. There’s still time to devise a retirement plan if you haven’t yet. (Hint: hoping to win a zillion-dollar lottery isn’t a plan.) You’re getting a late start and probably won’t be able to retire at 65, but with sound planning and sharp investments, you may be able to call it a career in your 70s.

2. A Hard Look – People are living longer and that means what was sufficient for a secure retirement in the past won’t cut it now. Remember that a late start limits your choices.

3. Hire A Financial Adviser – You need to find an adviser who specializes in retirement planning ASAP. The broad outlines of your plan call for setting aside as much money as possible and low-risk investments.

4. Stick To It – If you’ve been saving and investing for years, stick to the plan. Talk to your financial adviser. You probably want to start moving into less risky investments to preserve your capital. Ask your adviser about bonds and a certificate of deposit. Rule of thumb: the closer you get to retirement, the more conservative your investments should become.

5. Consider Part-Time Work – How many novels can you read and how many cruises can you take after retiring? The number of young workers is declining and if you want to work part-time, you probably can. The extra income would help and staying active would preclude your going nuts as you play 18 holes of golf for the 99th time.

Many brokerage firms have Web sites offering financial planning tips, including T. Rowe Price (TROW), Merrill Lynch (MER), Goldman Sachs (GS) and Morgan Stanley (MS). Major banks also offer solid information, including JPMorgan Chase (JPM), Bank of America (BAC), Citigroup (C) and Wells Fargo (WFC).