Want to get serious about preparing for retirement? Get a plan. A 2014 Wells Fargo survey found that middle-class Americans who have a written retirement plan saved four times as much as those without one. Fortunately, a plan doesn’t have to be complex to be effective. In fact, putting together a perfectly acceptable one can be as easy as 1-2-3.

Step #1: Pick a savings target. Don’t get hung up on trying to identify the exact amount need to save. When you’re saving for a retirement that’s many years off in the future, there are too many unknowables to be that precise. To get things rolling, I suggest you shoot for 15% of pay, which is the figure cited for the typical household by the Boston College Center For Retirement Research in a recent paper. If that amount seems too daunting, then start at 10% and boost that figure by one percentage point each year until you hit 15% of salary.

The important thing, though, is to push yourself a bit when it comes to saving, as there may be some years when unexpected expenses or a job layoff prevent you from reaching your savings goal. Indeed, when researchers for TIAA-Cref’s Ready-to-Retire survey asked retirees last year what they wished they had done differently to prepare for retirement, almost half said they wish they had saved more of their paycheck for retirement. They also expressed regret that they hadn’t started saving sooner, So once you pick your target saving rate, start stashing your dough away immediately.

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One more note about your savings rate: If you contribute to  a 401(k) or other workplace plan and your employer matches a portion of what you save, those employer matching funds should count toward your savings target. So if your company contributes 50% of the amount you save up to 6% of salary for a 3% match—a typical formula—you would have to save just 12% of salary to reach a 15%.

Step #2: Settle on your investing strategy. This step trips up people for several reasons. Some get flustered because they know little or nothing about investing. Others think they’ve got to sift through dozens of investments to find the “best” of the lot. Still others feel that they aren’t doing an adequate job investing for retirement unless they’ve stuffed their portfolio with every possible investment representing every conceivable asset class known to man.

I have one word for people worried about such issues: chill. Investing doesn’t have to be complicated. In fact, whether you’re a neophyte or a grizzled veteran of the financial markets, simpler is better when it comes to building a retirement portfolio.

Here’s all you have to do. First, restrict yourself to low-cost index funds. You can build a diversified portfolio with just two funds: a total U.S. stock market index fund and a total U.S. bond market index fund. If you want to get fancy, you can throw in a total international stock index fund. (If you prefer, you can use the ETF versions of such funds instead.) You can find these investments at such firms as Vanguard, Fidelity and Schwab.

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Second, settle on a stocks-bonds mix that’s appropriate given your tolerance for risk. You can get a recommended mix by going to the Investor Questionnaire-Allocation Tool in RealDealRetirement’s Toolbox. Once you’ve settled on a stocks-bonds mix, leave it alone, except perhaps to rebalance every year or so. Or, if you can’t see yourself building even a simple portfolio with a few funds, just invest in a target-date retirement fund. This type of fund—available from the same three firms mentioned above—gives you a fully diversified portfolio that becomes more conservative as you approach and enter retirement.

Step 3: Do an initial assessment. Now it’s time to see where you stand. That may seem premature if you’re really just getting started. But the idea is you want to get a sense of what kind of retirement you’ll end up with if you follow the course you’ve set in steps one and two. Think of it as establishing a baseline so you can gauge whether or not you’re making progress when you re-do this evaluation every 12 months or so.

Doing this assessment is pretty simple. Go to a retirement income calculator that uses Monte Carl0 analysis to make projections, plug in such information as your age, salary, savings rate, the amount, if any, you already have stashed in retirement accounts, the stocks-bonds mix you arrived at in step 2, the age at which you intend to retire, the percentage of pre-retirement income you’ll require in retirement (80% or so is a decent estimate) and how many years you expect to live in retirement (I suggest to age 95 to be on the conservative side)…and voila! The calculator will churn a few seconds and forecast the probability that you’ll be able to retire on schedule given how much you’re saving and how you’re investing.

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Generally, you’d like to see a probability of 80% or higher, although you shouldn’t freak out if your chances are much lower. The point of this exercise is to see where you stand now so you can adjust your planning to tilt the odds of success more in your favor, if that’s necessary. The most effective adjustment is saving more, but there are other possibilities, such as staying on the job longer, working part-time in retirement, maximizing Social Security benefits and relocating to a lower cost area once you retire.

Do you have to write all this down to get the benefit of this plan? I wouldn’t say it’s absolutely necessary. But I think it’s a good idea to jot down your target savings rate and the asset mix you’ve decided on if for no other reason than doing so can make you feel more committed to following through. You should also save a digital or hard copy each time you do an evaluation so you can see whether you’re making progress or backsliding.

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You’ll want to refine and tweak this plan as you go along, but for now the most important thing is to get started. Because the sooner you set a savings rate and start funding your retirement accounts, the better your chances of having a secure and enjoyable retirement down the road.  (4/21/15)

Walter Updegrave is the editor of RealDealRetirement.com. If you have a question on retirement or investing that you would like Walter to answer online, send it to him at walter@realdealretirement.com.