The worst body language mistake you can make has to do with your eyes

When it comes to body language, there are plenty of serious mistakes you can make.

It's hard to tell which slip up is the worst of the bunch, as they all can really warp how others view you.

So Business Insider reached out to Dr. Lillian Glass, communications and body language expert and author of "Toxic People," to get her opinion on which body language mistake is the most damaging.

Her pick: Bad eye contact.

She says making no eye contact can send the wrong message - but so can holding too strong of a gaze.

A lack of any eye contact may tell the person you're speaking to that you're not confident, you're not being honest, or you're not interested in what they are saying. But staring or looking directly into a person's eyes for too long "can be rude and make the other person feel uncomfortable," Glass explains.

Finding the right balance is key - and failing to do so is the worst body language mistake you can make.

To avoid sending the wrong message or creeping anyone out, Glass suggests varying your stare.

This means moving your gaze from the person's forehead, to their eyes, to their nose, to their mouth - while occasionally looking away.

"Doing this softens the gaze and makes you more approachable," Glass says. And that should always be your goal, especially when you're meeting someone for the very first time.