Slow start Some speakers don't seem to start at all they ramble into the presentation and fizzle out of it. You need to open every presentation in a way that breaks the audience's preoccupation and causes them to be present mentally as well as physically. You want to close a presentation with a summary or a call to action. Set intermediate times in your presentation to keep on track all the way through. Don't wait until the end to cut.
Few speakers use question and answer sessions effectively.
Speakers who do this show lack of respect for their audience. How you communicate your message is just as important as what your message is. Take the time to develop simple visuals, either props of some sort or visuals produced on a computer. Use graphics to put a picture in your audience's mind that supports any words you use on a visual. Test your visuals in advance of your presentation, preferably in the room where you will speak.