A LinkedIn profile pic may not seem like a big deal – it’s just a small head shot, after all – but if you’re selling books or a service associated with your title, it can help make…or break…a sale.

Indeed, research shows that those few pixels are worth spending more than a few seconds on. Face perception studies have found that people make instantaneous judgments about your competence, trustworthiness, and aggressiveness based a quick look at your mug. Given this, you want to make conscious choice about how you present yourself to the public, especially if just one photo is all you’ve got to make an impression.

For example, if you want to appear trustworthy (especially when you’re offering a service), look happy by smiling broadly (but naturally). Should you want to appear as if you are leader, a healthy-looking face is more important than one that appears intelligent.

Also, wear the clothes that fit the part. If you write westerns, show yourself in modern ranch clothes with a horse. Should you write literary pieces, try a black turtleneck. At the same time, you want to find balance so that your clothes don’t look cliché or silly. A science fiction writer dressed up as Chewbacca probably diminishes rather than helps people taking your seriously.

Regardless of which image you wish to convey, also stick with a head and shoulders shot. Anything else won’t show up as the profile pic is very small.

Never use party or vacation shots in your photos. They usually reveal more about you than what you’d like your book buyer or prospective client to know and send the message that you’re not professional (though there may be a time when sending such a message is the one you wish to convey). Outdated photos of yourself also are no-no. Finally, selfies almost always look unprofessional, showing you at an odd angle with bad lighting.

Yes, as mom said, people should “never judge a book its cover.” And we won’t. But potential clients and buyers of our books will. So for them, we need to choose the best photo.