The stock market crash after the Internet bubble destroyed portfolios -- and dreams. The Nasdaq fell from 5,000 to less than 1,200, nearly an 80% decline. And that's only an average. Many stocks became essentially worthless. The tragedy wasn't in the numbers, but in the effect those losses had on people. Many investors were completely wiped out, losing money they'd been saving for years.

This really isn't the sort of pain you want to experience firsthand. That's why it makes sense for all investors to have a portfolio that's prepared for lean times. If a terrible day ever comes, you'll want to make sure you only suffer a flesh wound, not decapitation.

At Motley Fool Inside Value, we focus on identifying stocks that not only outperform on the upside, but can also survive a crash relatively unscathed.

Diversify now
Investors with technology-focused portfolios suffered the most a few years ago. There was almost nowhere in the sector to hide, with even the strongest companies suffering huge declines. Yahoo! (NASDAQ:YHOO) fell 95%, SanDisk (NASDAQ:SNDK) dropped 90%, and EMC (NYSE:EMC) plummeted 95%. Even now, these companies aren't close to their pre-bubble highs. And again, these are some of the strongest companies in the sector.

The moral of the story isn't that technology companies are risky, but rather that diversification is a key component of a crash-resistant portfolio. While tech has been dreadful, the Vanguard REIT Index would have more than doubled your money since 2000, and energy stocks have had outstanding returns as well.

A diversified portfolio that included technology, real estate investment trusts, and oil would have prospered. Diversification also ensures that you get the full benefit of your stock-selection skills. Being the best of the losers doesn't make you a winner. But if you pick the best of each sector, you'll do quite well.

Buy cash
The companies that fell the most when the bubble burst had one big problem: They had neat ideas, but didn't actually make any money. Before the crash, even incredibly popular companies such as Vignette were drowning in red ink, never logging a profitable year. But investors assumed that Vignette would be a great investment, because its products targeted the hot Web-applications niche. That was a costly mistake.

Unprofitable companies have little flexibility in bad business climates, and they tend to do poorly in bear markets. In a panic, investors won't buy dreams. They'll stick with consistent cash machines, steady blue-chip companies such as Kimberly Clark (NYSE:KMB) and Quest Diagnostics (NYSE:DGX). It's no coincidence that these two companies show spectacular long-term returns -- and were largely unfazed by the last bear market.

Businesses that earn gobs of cash don't have to raise money to survive. They can even take advantage of poor conditions to gain market share from weaker competitors. Such businesses tend to be crash-resistant.

Be skeptical
Maintaining a healthy level of skepticism is one of the best ways to guard your portfolio against a market crash. Wall Street isn't a charity; it's a bunch of businesses focused on making money for themselves. Helping small investors make a profit is item No. 382 on the list of Wall Street priorities, immediately below ensuring that the new assistant knows exactly the right amount of milk and sugar to put in everyone's morning coffee.

Be skeptical of analyst forecasts, whether it's a prediction that oil will hit $200 a barrel or that First Solar (NASDAQ:FSLR) will hit $450 a share, as at least one analyst has predicted.

Rather than blindly trusting the analysts, make sure you know the companies you're buying. Understand what risks each business faces, and what competitive advantages will help the company overcome hurdles. Be particularly wary of high growth estimates, because analysts tend to be optimistic, and high growth is difficult to sustain. If the company fails to achieve overly ambitious growth estimates, the stock will get hammered.

Finally, buy a stock only if conservative analysis shows that the company is trading at a bargain price. Since stocks tend to return to their intrinsic values, buying below that value provides significant protection in a crash.

Foolish final word
While a crash will hurt any portfolio, a few carefully chosen strategies can help you avoid the worst -- and give you the opportunity for big gains along the way. If you're interested in reading our recommendations at Inside Value, we offer a free, no-risk 30-day trial, which gives you access to all issues, a discounted cash flow calculator, and dedicated discussion boards.

Whatever you do, start planning your blueprint for a bear-resistant portfolio.

This article was originally published Sept. 28, 2005. It has been updated.

Fool contributor Richard Gibbons is scared of stock market crashes, large flying objects, and eerie music. He owns shares of Quest Diagnostics. Quest Diagnostics is an Inside Value recommendation. Kimberly Clark is an Income Investor choice. The Motley Fool has a disclosure policy.