Don't try to be funny. Most people who are nervous on stage tend towards joke telling, puns and bad one-liners. As a professional entertainer you have no business doing this. Let the humour come from the magic you're performing. Contrived lines and "bits of business" that are rehearsed will sound rehearsed. There is nothing worse than humour badly executed by paid entertainment. Don't laugh at your own jokes, wait until your audience does and even then a smile is best.