Have you heard of the trick where you can get people to like you by getting them to do small favors for you? Examples include getting them to: loan you a book, help you through an important decision, or watch your dog for a day.

You can reverse this trick, and make yourself like other people by doing small favors for them. Offer to loan someone a book, offer to pick up a tab for something small, etc.

Before you know it, you'll like everybody. Actually liking everybody leads to being nice.