Several studies show that participants underestimated how happy another person would be to hear praise and overestimated how cringe-worthy they would find the exchange. 

• Participants worry they will articulate the compliment wrongly. But the research shows that the recipient only cares how nice the praise is.
• Another fear is that overcomplimenting might make some people bored of your praise or find it tiresome. However, even this reaction is far less likely than we think.

A compliment is an effective way to make other people feel happy. And it doesn't cost you a thing.

• Context is important. It is not proper to compliment someone's appearance if there's a risk of objectifying them.
• Stick to compliments that really convey someone's social value. For example, praise on a presentation or the way someone handled a difficult client.
• If you have a kind thought that shows respect to the other person, share it.