As a communicator it's vitally important to speak with credibility. When you have it...90% of the work to convey your message to someone else is done!
Here are a few great ways to build credibility...
1. Know your subject backwards and forwards, inside and out. If someone asks you a question and you do not know the answer 100% - tell them you do not know and get them the answer at another time. OR...send them to someone else.
2. Speak as you normally would. Do not try to be too polished. This comes off as insincere. Does Bill Gates need to take speaking lessons to speak publically about computers?
3. Walk your talk. If you're telling someone they need to do something - make sure you are doing it or have done it in the past.
4. Don't pretend to know everything. Only speak about subjects your qualified to address. Do you really think everyone believes your that smart anyway?
5. Have fun. Remember...enthusiasm is contagious.
6. Talk about positive subjects. In the end...most people you talk to can care less about your personal problems.
7. Lighten up on the gossip. You cannot make yourself taller by ripping down others. Anyone with half-a-brain knows that if you're gossiping about someone to them - you will gossip about them to someone else. Most gossips are losers!
8. Speak your opinion. Most people are corporate yes-men losers. Stand up for yourself and be your own person.
9. Watch the profanities. You will come off as boorish - a philistine at best. What good are they anyway?
10. If you have nothing nice to say about anyone...REFRAIN. It will do you no good - so why bother?
BONUS TIP: Put nothing in an e-mail, voicemail, video, or any written format that can come back and bite you in the behind. Everytime you write/say something in a format that can be recorded or written down - think real hard if you really want it on record.