Kiplinger encourages investors to react to this year’s stock-market plunge much in the same way you would react to a sale at the corner story: Grab your wallet and go on a shopping spree.

However, a savvy investor will do their homework beforehand and resist impulsive buys.

“When a stock’s price falls sharply, few investors react with giddiness at the prospect of getting something for less,” explains Kiplinger’s James K. Glassman. “More likely — especially if they already own the stock — they respond with anxiety or cold fear. Rather than buy the stock, they’re more apt to sell it,” he wrote.

Glassman added: Warren Buffett, the most successful stock investor of modern times, put it well: “Look at market fluctuations as your friend rather than your enemy.”

Here are Glassman’s 4 tips:

• Think of buying a stock as becoming a minority partner in the business. “When the price falls, you can acquire a bigger stake in the business for less. But you have to have confidence in the business itself. And it’s even better if you love it,” he said, citing such personal favorites as NetFlix and Whole Foods.
• Avoid the psychological torment of falling share prices by engaging in dollar-cost averaging. “Put a set amount of money into a stock or mutual fund each month or quarter or year,” he said. “If you invest $1,000 a month and the stock you love trades at $100, you’ll add 10 shares to your portfolio. If the stock plummets to $83 the next month, your $1,000 will fetch 12 shares. Instead of feeling as if you’re losing wealth, you’ll feel as if you’re gaining it.”
• Capitalize on the myopia of your fellow investors. "When a company runs into trouble, Mr. Market frequently assumes that the problem will continue. The truth is that you don’t have to know how a company will solve its current problem," he said, citing McDonald's recent woes and subsequent resurgence.
• Make a wish list. "Write down a few companies you would be thrilled to own at lower prices," he said.

But successful investing truly can be an art form. While a volatile market can be one investor’s worst enemy, it can be another investor’s best friend.

“Times are tough for billionaire investors. Warren Buffett's top stock picks aren't working — whether it's IBM or American Express, the Oracle can't seem to catch a break,” CNBC reported.

Buffett had his worst year since the financial crisis in 2015.

Related Stories:

• Fidelity Fund Manager: 6 Keys for Picking Winning Stocks
• SocGen's Edwards: Buy Treasury Bonds Even as 'Ice Age' Is Questioned