Public Speaking is a skill and an art.
Public speaking may come easier to some rather than to others, but it can be learned.
A great number of mistakes come from the fear of putting oneself on the line and being vulnerable to criticism.
Hence the white-knuckled grip of the dais, the wringing of hands and the use of fillers such as ums and ahs.
Other mistakes occur because of a lack of knowledge.
This includes knowledge of your audience demographics, of a proper dress code, or of good slide presentations.
Below is a list of some of the common mistakes speakers make and how to handle them.

1. Speak too long.
   Your audience may fall asleep, or start leaving.
   Say what you have to say, conclude your speech and exit graciously.
   
2. Do not know their audience.
   Your audience will not pay attention if you do not address their needs or speak in their language.
   It is important to research the demographics and sophistication of your audience.
   
3. Wear distracting clothing and accessories.
   Your audience wants to hear what you say, not to see what you wear.
   Refrain from wearing bright clothing, sparkling jewelry and clanging bracelets.
   
4. Walk rapidly back and forth on stage.
   This makes your audience dizzy or uncomfortable, and distracts from your message.
   Plan your moves to emphasize your points and to include your entire audience.
   
5. Grip the podium tightly and remain in one spot.
   This stance lacks dynamism and is very boring for the audience.
   Use the entire stage and/or move into the audience to keep their attention.
   
6. Continuously wring hands.
   Shows nervousness and makes your audience nervous.
   Use your hands to make appropriate gestures and leave them at your sides when not gesturing.
   
7. Use lots of clichés.
   Unimaginative and you lose credibility with the audience.
   Avoid clichés altogether, use your dictionary and thesaurus to find better ways of expressing your ideas.
   
8. Make inappropriate jokes.
   Your audience will not appreciate this and it leaves them with a poor impression of you.
   Telling jokes is a skill.
   Find jokes on the internet, adapt them to make them personable, and rehearse for timing and effect.
   
9. Use fillers such as ums and ahs This is annoying and distracting for the audience.
   Rehearse your speech thoroughly, ask a close friend or family member to monitor your fillers and work at eliminating them.
   
10. Present crowded slides.
    Your audience cannot concentrate on all that is shown, and often cannot read the size of print.
    Use no more than 4 or 5 points on a slide, each being a short sentence.
    Understanding why mistakes are made and how to handle them can greatly improve your public speaking skills.
    Of course, knowledge is nothing without practice.
    Practice with a voice recorder or video, practice before your family and close friends, practice before a small and forgiving audience.
    Soon, you will overcome your fears and increase your knowledge and skills in the art of public speaking.