"We all secretly like compliments, even if we disagree with the flattering remark. Think about how a simple compliment can change your whole attitude. How it positively impacts your self confidence, even if it's only for one second. Now, think about that one time someone complimented you, and you never forgot what they said, because it really meant something.
So pass that good feeling forward. An appearance compliment is something nice to receive, but sometimes what's better is a a compliment about what's on the inside, what you admire about their personality, or that they have a kind heart.
When someone notices the unseen traits that one pertains, it's a more meaningful thought. So, go out and compliment the girl that has a unique mind. The boy that has a great sense of humor, but goes unnoticed. Tell her that you admire her positive attitude or his ambitious perspective on succeeding in life. A compliment that comes from the heart, goes to the heart.