I stutter and have made a lot of presentations for work. I never wing it. I write my speech up on note cards and practice it by myself at least 10 times. That sounds like a lot but I make tweaks and then try it again with the tweaks. Once I am done tweaking it, I then practice it a few more times. This also helps "cut out the fat" of the presentation. If you have data that requires supporting documentation, I always have that readily available in case of questions. Nothing like being put on the spot to bring out the worst in your stuttering. A lot of practicing also makes me more relaxed which makes me joke more thereby creating a more enjoyable presentation. I always get compliments on my presentations and it is a result of my stuttering. If I did not stutter, I probably would not practice as much. I love doing presentations. I stutter a lot in normal conversations so it is my time to prove myself, at least in my mind.