Keep Smiling- It will add value to your faceTo smile is a good habit. Don't laugh at others. But smile at others. If you are smiling you will appear more pretty.
People like to talk to others who will always have a smile on their face. If you are very serious no smile on your face, nobody likes to talk to you and you can't become friendly with others.
Small kids also show their happiness if you smile at them. Instead of that if you are serious, no kid will see your face and play with you.
Smile is an indication of happiness and satisfaction. A smiling man is always happy.