Take some sort of an acting/improv/public speaking class or read tutorials on the subject. These will teach the basics of patter.
Before performing, make a list of the tricks you plan to perform.
Know all of the steps needed to complete each trick.
Understand that your spectator is what will make the trick. You need to keep them interested.
Be natural! Imagine how you would like a magician to speak to you.
Be sure to explain everything very carefully. The worst spectator is a confused spectator.
Never be condescending. Even if you are acting in a character, do not treat your spectators like dirt with your patter. Always be very respectful with your patter.