On July 16, 1993, when The Washington Post published my first column on investing, the Dow Jones industrial average stood at 3528. Today, as I complete my final column for The Post, the Dow is well over 10,000.

Including dividends, the market has returned an incredible 242 percent in less than six years.

I can't take any credit for that spectacular performance, but I hope I can take some credit for encouraging readers to participate in it.

Why walk away from a popular column? The main reason is that I think six years is long enough to do any one thing. I have written a book, "Dow 36,000," which will be out in the fall. I will continue to write articles from time to time -- but not at the pace of 100-plus columns a year.

The best part of writing for The Post, the International Herald Tribune and the dozens of other newspapers that run my column is the response I get from readers, especially the ones who say I have helped them invest intelligently and stay in the market during scary times.

Since Howard Kurtz mentioned in The Post last week that I was leaving, I have heard from many of you. One reader said in an e-mail: "Of all the people out there offering financial advice . . ., I have come to trust and rely on only two -- you and another, whose name, for the life of me, escapes me at the moment."

I'm glad to be in such distinguished company.

In fact, this has not been so much a column of advice -- buy this stock, sell that one -- as of education. The problem is that there is only so much a writer can teach readers about investing, and I often felt that I was repeating myself. On the other hand, repetition provides a sense of comfort.

So, for old time's sake, let me repeat once more. Here are 10 truths about stocks, often seen in this column, to clip and save:

1. Before you invest a penny, answer some questions about your own situation: when you plan to retire, how averse you are to risk, how much income you're likely to need to meet living expenses. Then decide how much you'll put into stocks, bonds and cash. Those allocations should change over time, but you shouldn't deviate from your plan. Asset allocation is the first and most important step in investing.

2. Start early. The most critical element in investing success is time, not stock picking. Young people have an enormous advantage. If the market continues its annual average returns since 1926, $5,000 invested today by a 25-year-old will become $320,000 by age 65.

3. Stocks are investments for the long run, which in my definition is at least seven years. If you can't stay in stocks that long, stay out. In the short term, stocks are very volatile (their prices fluctuate wildly), but in the long term, they are no more risky than Treasury bonds -- and they return a lot more. In fact, stocks, for the long-term investor, are a miraculous gift. If the averages of the past 200 years hold, you can double your money in 6 1/2 years and barely lift a finger.

4. Don't try to "time" the market. Market timing -- buying or selling stocks in anticipation of the market's next move -- is a fool's errand. "After nearly fifty years in this business," writes John Bogle, founder of the Vanguard Group in his excellent book, "Common Sense on Mutual Funds," "I do not know of anybody who has done it successfully and consistently. I don't know anybody who knows anybody who has done it successfully and consistently."

Why try? A reasonable assumption is that all stocks are priced about where they should be. Buy not on the basis of price, but on the soundness of the company and the likelihood that its earnings will rise. Buy good businesses and hold on for dear life.

5. The best time to sell a stock is never. Sell if something important has happened to the company -- new management is falling down on the job, competition has entered its market niche or a key product has failed. Don't sell because a stock's price is too high -- or, especially, if it is too low. Also, remember that you can't tell whether to sell a stock unless you know why you bought it in the first place.

As Warren Buffett, chairman of Berkshire Hathaway Inc. and the best investor of our time, has written: "Inactivity strikes us as intelligent behavior. Neither we nor most business managers would dream of feverishly trading highly-profitable subsidiaries because a small move in the Federal Reserve's discount rate was predicted or because some Wall Street pundit had reversed his view on the market. Why, then, should we behave differently with our minority positions in wonderful businesses?"

That's a good point to remember at a time when the market is in a tizzy over the Fed's next step. I don't care what the Fed does next; I care only whether the management of Cisco Systems Inc. is on the ball.

6. Diversification is essential. You should own a portfolio that includes small-caps, foreign companies, real estate and value shares, whether those stocks are in favor or not. A portfolio that is too concentrated will be too volatile, so you will be more likely to get scared and bail out at the wrong time. Still, don't diversify to the point that you don't know what you own or why you bought it. A dozen stocks is enough, and 20 should be the maximum.

7. Mutual funds are magnificent, democratic inventions: They provide diversified portfolios chosen by experts. But funds also have their drawbacks. Some are just too expensive, and the average fund has not been able to beat the Standard & Poor's 500 over the past decade. My preference is to own three or four mutual funds (especially those that specialize in sectors of the market, such as small-caps or international stocks) and to own individual stocks for the large-cap part of your portfolio.

8. Most investors can't do it themselves. They need help, not so much with stock picking as with asset allocation and hand-holding after they have made their purchases.

As the great Benjamin Graham, mentor to Warren Buffett, wrote, "The investor's chief problem -- and even his worst enemy -- is likely to be himself." Stocks stir emotions, and a broker or adviser can ask "Why?" when you call in a panic, demanding to sell.

The most powerful piece of research I have seen is a study by Dalbar Inc. that shows that, over the past dozen years, the average investor has achieved returns that are only one-quarter those of the market as a whole -- because of jumping in and out of stocks at the wrong times.

9. When it comes to bonds, the new Treasury Inflation-Protection Securities are remarkable investment vehicles and have been almost completely overlooked by the public. Indexed to the rise in consumer prices, they guarantee a real rate of return of about 3.8 percent. Unless the U.S. government goes broke, they are risk-free.

10. On Internet stocks, which are what I am asked about most often: It's fine to own them, but don't get carried away. I never joined in when the sophisticates were laughing at Web stock valuations; still, I think it's a mistake to commit more than 15 percent of your portfolio to companies whose future earnings can't be forecast.

This decalogue should not come as a surprise to anyone who has read even a few of the hundreds of columns I have written for The Post. But it's nice to be reminded one more time -- and nice to do the reminding. Cheers.