How to compliment people

From "Why Compliments Terrify Us" by Elizabeth Bernstein for the Wall Street Journal

• Be sincere.
• Be selective. Think Goldilocks. Not too big or too small. 
• Be specific. Don't say" You look pretty today. Say: That sweater really brings out the color of your eyes. 
• Show impact. Tell people how they have positively affected you. Instead of "I like your column today," try "Your story made me run out and complement a stranger. 

When you receive a compliment, just say thank you. Be gracious, not self-deprecating. Don't worry about returning the praise. It's a compliment, not a volley.