Suppose you're speaking at an event where you've already been introduced, or the audience already knew who was coming to the event, its not a good idea to keep repeating yourself. Instead of telling the attendees your qualifications, again and again, try doing something different and opting for qualities that the introduction from someone else didn't tell them already. Remember, the introduction is the 30 seconds that will tell the watchers whether you're someone they should be listening to or not.