Naturally, you’ll want to rehearse your presentation multiple times. While it can be difficult for those with packed schedules to spare time to practice, it’s essential if you want to deliver a rousing presentation. I’m famous around the office for staying up late the night before a big presentation, practicing over and over. If you really want to sound great, write out your speech rather than taking chances winging it – if you get nervous about speaking, a script is your best friend.
Try to practice where you’ll be delivering your talk. Some acting strategists suggest rehearsing lines in various positions – standing up, sitting down, with arms open wide, on one leg, while sitting on the toilet, etc. (OK, that last one may be optional.) The more you mix up your position and setting, the more comfortable you’ll feel with your speech. Do a practice run for a friend or colleague, or try recording your presentation and playing it back to evaluate which areas need work. Listening to recordings of your past talks can clue you in to bad habits you may be unaware of, as well as inspiring the age-old question: “Is that what I really sound like?”
From: http://www.wordstream.com/blog/ws/2014/11/19/how-to-improve-presentation-skills