According to Mehrabian (1971), voice, tone inflection, posture, gestures and eye contact have a much greater impact on the audience than content.  This has some interesting implications for you as a speaker.  It is extremely important as a speaker to:

• Be aware of distracting habits
  Often we are unaware of habits that we have that can be distracting to audiences.  These could include rocking, swaying, fidgeting, or even repeating certain words, for example ‘Ummm’.  It can be a good idea to have a friend critique you whilst rehearsing as they may be able to pick up on some of these habits.
• Be aware of posture
  Posture can integral in convincing your audience to listen.  It is important to stand up tall, as this will demonstrate confidence. Slouching, on the other hand, has the opposite effect.
• Engage with audience
  An easy way to ensure you engage your audience is to use effective eye contact.  Asking questions, using gestures, or developing activities for your audience members is also another way to ensure that they stay focused on your presentation.
• Make it easy for your audience to listen to you
  Audience members are likely to ‘switch off’ if you speak too quickly, too slowly, or too quietly.  Don’t give them an excuse not to listen; speak confidently, and be aware of your pitch, volume, rate, as well as your use of pauses.
  
• Be interested in your subject matter
  If you’re not interested, why should your audience be?