8. Be spontaneous but succinct.
Mastering spontaneity comes from mastering your presentation. Know your material like the back of your hand to successfully make it look natural. The best comedians appear to 'wing' their acts, when they actually present their content hundreds of times and perfect the delivery.
9. Avoid asking insultingly obvious questions.
We've all seen speakers ask the audience to raise their hands for blatantly obvious questions. It wreaks of desperation and usually annoys about half the audience anyway. If you already know what you're going to say regardless of how many people raise their hands, then the question is unnecessary. Stick with asking questions that you actually care what the answers are.
10. Be original.
Try not to walk like, talk like, and look like, the professional speakers you admire. Because if you admire them, chances are so does the rest of the world. If you just try imitating them it will make the audience realize how much they miss the original. You never want to have someone in your audience say "You remind me of so and so." What you want is for them to say: "you're like no one I've ever heard before."