NEW YORK (CNN/Money) - My husband and I are 36 years old and have no retirement investments except a Roth IRA we recently opened with $300. We're concerned about saving for retirement, but we can only put away small amounts of money and don't know where to begin. Can you give us some direction? We are lost.

-- Mary Tolen, Pompton Lakes, New Jersey

Hey, go a little bit easier on yourself. Sure, it would be nice if you and your hubby had begun saving years ago and had tons of dough stashed away. But you're still doing a better job than a lot of people.

After all, you at least are thinking about retirement and are motivated enough to write me -- that's more than a lot of people are doing. What's more, you've actually done something. You've put a few bucks away. Granted, it's not a fortune. But it's a start.

The trick is to keep the ball rolling. So how do you do that? No big secret there. In fact, you kind of got at the answer in your question when you said "we can only put away small amounts of money." But guess what? That's exactly how most of us save. We put away small amounts of money as often as we can.

In fact, I'd say that's the single most important thing you can do. Save regularly. Most people have the mistaken notion that fancy investing techniques or picking the right stock or mutual fund is that most important aspect of retirement planning.

Baloney. If you manage to save regularly, you can accumulate a decent nest egg by retirement even if you earn only average rates of return. Just as an example, let's say that you and your husband manage to put $100 a month into your Roth IRA and earn an 8 percent rate of return. Over the course of the next 30 years, your Roth would be worth something in the neighborhood of $140,000.

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This isn't guaranteed, of course. You don't know what rate of return you'll earn, and whatever it is you won't get it year after year like clockwork. But the point is the earlier you get started, the longer your savings -- and the earnings on your savings -- can work for you. And the greater your chances of accumulating a decent retirement stash.

If you don't manage to save much, however, then the greatest investments in the world aren't going to do much for you. I don't want to go Zen on you here, but terrific investing with lousy savings habits is like the sound of one hand clapping. I'm not exactly sure what that means, grasshopper, but you get the idea.

So the first thing I recommend you and your hubby do is set a monthly savings target. The figure should be high enough so you have to maintain a bit of spending discipline to make it, but not so high that you'll get discouraged and quit. Whatever that figure is -- $500, $300, $100, $50 a month, whatever -- increase it as your income rises.

Now for the investing part of your plan. You and your husband are investing for a retirement that is 30 years or more in the future. That argues for investing mostly in stocks (or, more likely in your case, stock mutual funds), although I think it's always a good idea to own some bonds (or bond mutual funds) too just so you don't panic when the market goes down.

As for the specific stock and bond funds you ought to buy, well, I can tell you that I'm partial to index funds because they have low expenses and give you an element of certainty. Not certainty in the sense that you know what return you'll earn, but certainty in that you know what exactly what kind of stocks you'll own. But actively managed funds can do well too, although I'd advise you to favor ones with low expense over those with high fees.

For tips on how to create a portfolio for your retirement savings, you can check out our Asset Allocator. You'll also find some fund suggestions there, although you can also screen for more choices using such criteria as annual expenses and minimum initial investment at our Fund Screener.

So set that savings target and start putting your money each month. It won't be long before you find that your $300 has grown to $3,000, and your $3,000 to $30,000 and your $30,000 to...

Walter Updegrave is a senior editor at MONEY Magazine and is the author of "Investing for the Financially Challenged."