Recently Donald Michael Kraig made a post about workshops and the need to develop more better presentation skills. He made some good points about the need to practice your presentation skills, and not rely too heavily on your visual aides. I agree with him completely, but I also think that there's another level to be explored when it comes to workshop presentation and that's the magical level. When I get booked for a workshop, one of the practices that I do involves creating a mental mansion for the workshop. I create talking points and exercises for the workshop and then what I do is create symbols I associate with those talking points and workshops and I place the symbols into the mansion. When I rehearse a workshop I visit the mansion and access the symbols to draw on the stored information. When I present the workshop I can use the same technique to access the information. This helps immensely with confidence for the presentation.
Another practice I do involves some energy work and personas. When I'm getting ready to do a workshop, I think about the energy I want to project to people. Are there specific emotions I want to draw on? If there are, then I'll draw on those emotions for the presentation. For instance I like to draw on confidence and charisma. they are excellent emotional energies for a presentation. I also draw on personas for my presentations. I'll think about people, pop culture characters, deities, etc that personify professional speaking. I'll then visualize myself drawing on the characteristics of those people, pop culture characters, etc to create a "suit" to wear. I then imagine that I'm wearing that suit and drawing on those characteristics while I'm speaking.
Of course what helps the most is to practice your professional speaking. You might consider joining a toast masters or similar organization where you need to speak, or taking on a part time teaching opportunity so that you can practice speaking to people. You might even take acting classes. If you want to become a better speaker there are lots of ways to do it, some mundane and some magical. I recommend using both.