One of the most difficult things a leader has to do is identify and develop other leaders in their midst.

Too often, organizations promote people based on competency, not on leadership potential–the so-called Peter Principle (the theory that employees get promoted to a level where they are incompetent), says leadership expert Tom Rath, author of the best-selling leadership book StrengthsFinder 2.0. While someone may be a very good salesperson or accountant, that person should also be a good leader before you put him or her in charge of others, Rath says.

“You need to watch out that you’re really evaluating someone’s potential to lead others–not just whether they deserve to be upgraded or promoted in a hierarchy that probably isn’t structured right,” he says.

So, what clues should you be exploring when it comes finding people with the best leadership potential? As you go about your day, look for these prospects.

People who are sought out by others for their advice and insight deserve a close look under the leadership lens, says Robert Vanourek, former CEO of five companies and author of Triple Crown Leadership: Building Excellent, Ethical, and Enduring Organizations. These are typically people who are smart and also have good people skills. They don’t let ego or arrogance get in the way of helping others, which wins them the respect that leaders need to be effective, he says.

When you have an employee with that “never say die” attitude, who looks for solutions and doesn’t make excuses, you likely have a solid leadership candidate on your hands, Vanourek says. When your team encounters a setback, look for the person who starts spouting possible plans of attack instead of defeatist attitudes. Leaders need such optimism and persistence in the face of adversity, he says.

Rath looks for people who can inspire others toward a common cause or goal. While observing many leaders over the years, he says some of the best have exhibited this ability even very early on in their careers, before they had any formal management responsibility. Most people are more focused in developing themselves than rallying others for the good of all.