This is from Ben Arment's blog here. It is way too funny for those of us who occasionally speak:
1. Ask some trusted but truthful people to give you feedback. Preferably people who don't call you "boss."
2. Videotape yourself preaching and watch it every Monday.
3. Get rid of the "preacher voice." Syllables are not suggestions.
4. Read James Humes' book "Speak Like Churchill, Stand Like Lincoln."
5. Quit listening to your favorite preacher, trying to borrow his convictions. Yes, I'm talking to you, Mark Driscoll lover.
6. If you say that you're preaching an expository sermon during your message, you're not preaching an expository sermon. It's like the word "breezy." You can't say "breezy."
7. Ask your wife. Unless you have a tendency to yell at her when she's truthful with you. Then you probably shouldn't be preaching in the first place.
8. If you were an animal preaching -- hang with me here -- what kind of animal would you be? Now... do people typically shoot that kind of animal?
9. Use at least 25% of your sermon planning time to focus on structure, not just content.
10. Go to a conference for communicators in ministry. Like, say,STORY.
BONUS percentage points: Ask another local pastor to give you feedback. I did. It was humiliating to be studied, but ultimately beneficial.