A good level of general awareness will come in handy so that you aren't at a loss of words on certain issues. Understand the topic and analyse it mentally before speaking. Be clear about the purpose and content of your viewpoint.
One should be able to communicate his views in an effective manner to everyone. Be clear in speech, audible but not too loud and above all remain confident.

Remember the six C's of effective communication -- Clarity, Completeness, Conciseness, Confidence, Correctness and Courtesy. You should mantain eye contact with all others in the group and not focus on a particular person for he may benefit from that. Be responsive to ideas from other people and seem to be very receptive and open-minded but don't allow others to change your own
viewpoint..