Listen first, communication is a two-way process; getting your message across depends on understanding the other person
Don't overreact to problems or situations
Use the right words when trying to get your point across
Smile and use eye contact
Be interested in what your co-workers are talking about
Be relaxed - give off positive body language
Do not hunch shoulders, fidget, toe-tapping or twist hair because this gives the impression that you aren't interested in what the other person is talking about
Ask questions, it is a great way to show people that you are interested in them