Comment by onion2k

13. Have a message you're actually enthusiastic to tell people.

The audience can quickly tell if someone is there because they want to talk about the topic they're presenting, and having a receptive audience makes it much easier to get on stage to talk about it. If the audience knows you're there because you want another line on your resume or because you're trying to sell them something the atmosphere can turn quite cold and that is a world of pain for a speaker.