The speed of your smile can influence people's first impressions of you, research has shown.
Smile too quickly and others may think you insincere, while slow grins are generally perceived to be more genuine, according to the study.
The Go Group, which gives advice to fledgling businesses, looked at how smiling can contribute to making a positive impression.
The group's findings suggest that a smile that appears too swiftly and does not extend to the eyes sends signals to the other person that you lack sincerity.
Bridget Hanna, an occupational psychologist at Glasgow Caledonian University, said: "People smile for lots of different reasons. Smiling itself can help bind people together so it's a useful tool for business.
"Smiling immediately, all of the time, comes across as over-pleasing and lowers your status."
Smiles to avoid for business: