Yes, Toastmasters is probably the best thing for anyone who has to deliver public speeches and isn't comfortable doing it.
Rule #1
KNOW YOUR STUFF inside out. Especially if it's serious talk to serious people. No matter how uncomfortable you are, if you project the image that you KNOW what you're talking about and not just faking it, you'll do just fine. Keep it as simple as possible, relate the facts, numbers, etc., don't try to impress with big words or elaborate vocabulary.
Rule #2
KNOW your audience. What are they there for? What do THEY want to hear from you? It's not so much what you say that is important, it's HOW you say it and how it is perceived by your audience.
Rule #3
Speak loud and clear, but don't shout.
Nothing better than a monotone voice to put the whole room to sleep, and fast. Try not to hesitate too much or look for your words, make sure you're well prepared but don't give the impression that you're babbling from memory.
Rule #4
Make eye contact with people in the room, most importantly those you want to impress, do business with, etc.
Don't just talk and talk and talk, try to incorporate images, graphics, or a slide presentation. Make it colorful with vibrant or vivid colors without looking like a rainbow or fireworks.
Ask questions, make people think for a few seconds, then give the answer. Try to interact with them, bring them into your speech indirectly.
I would leave generic jokes completely out of your speech, you never know who you're going to offend, there's always someone who's going to take something the wrong way.
Best of luck with your speech!
Missie