Most investors should stick with a diversified mix of low-cost index funds and exchange-traded funds. For those who want to try stock picking, it's best to keep it to 10 percent of your overall holdings. Here are five habits you'll also need to be successful:

Check your emotions at the door

"Success in investing doesn't correlate with IQ. … What you need is the temperament to control the urges that get other people into trouble in investing." That's wisdom from Warren Buffett. Trading overactivity triggered by emotions is one of the most common ways investors hurt their own portfolio returns.

Pick companies, not ticker symbols

Don't let stock picking become an abstract concept. Remember: Buying a share of a company's stock makes you a part owner of that business. You'll come across an overwhelming amount of information as you screen potential business partners. But it's easier to hone in on the right stuff when wearing a "business buyer" hat.

Plan ahead for panicky times

All investors are sometimes tempted to change their relationship statuses with their stocks. But making heat-of-the-moment decisions can lead to the classic investing gaffe: buying high and selling low. Here's where journaling helps. Write down what makes every stock in your portfolio worthy of a commitment and, while your head is clear, the circumstances that would justify a breakup.

Build up positions gradually

Time, not timing, is an investor's superpower. The most successful investors buy businesses because they expect to be rewarded — via share price appreciation, dividends, etc. — over years or even decades. That means you can take your time in buying, too.

Avoid trading overactivity

Checking in on your stocks once per quarter — such as when you receive quarterly reports — is plenty. When one of your stocks experiences a sharp price movement find out what triggered the event. Rarely is short-term noise relevant to how a well-chosen company performs over the long term. It's how investors react to the noise that really matters.