We hear it all the time: Never accept the first offer. Don't leave money on the table. Push for more.

But should you ever not negotiate your salary? Many people don't. Only 39 percent of people negotiated their last salary, a study by Robert Half found. The 61 percent of people who didn't negotiate may have been onto something.

When you should accept an offer on the spot

Suzy Welch, former editor-in-chief of Harvard Business Review and bestselling author, offers her negotiation tips in a recent video for CNBC's Make It. Here's her top one: If the offer is within 10-15 percent of the salary you were hoping for, take it. Don't negotiate.

If it's already a good offer, Welch says negotiating for a few percent more could damage to your reputation. When you show up to your first day of work, you'll be starting off on a bad foot. "You want to walk in as a team player and come in as a person who believes pay comes with performance," Welch says.

Play the long game

This doesn't mean you're tied to that starting salary forever. Skipping the negotiation conversation at the start means you can save it for later -- after you've proven yourself as a stand-out employee who adds value to the company. Be the person who brings solutions. Then, you'll have more leveraging power than ever.

Six months into the job, Welch recommends asking for a significant raise. If you have specific examples of ways in which you've over-delivered, it should be a slam-dunk. They shouldn't be able to say no.

"I'm not saying be passive," Welch reiterates. "I'm saying be strategic. Go in with good will, do a great job, and in the long run you'll see the real reward."