Anyone who speaks because of their professional should always be improving their speaking abilities. One of the best ways is to become involved in learning different skill sets.
If you have never taken a comedy or improvisation class, seriously think about doing this. These 2 classes expand your ability to speak. Taking a comedy class is a great way to learn the structure of humor. It won’t make you a comic, thank god, but once you learn how humor works, you can begin placing it in your presentations. The good news is that if you attempt to say something funny and it is not, then simply move on.
Taking an improvisation class will teach you how to think on your feet. It will also start your creative juices flowing. So if in the middle of your presentation, you get a great idea, you will learn to expand that idea or thought into something larger.
Don’t be afraid. Take a class. Watch the fun happen!