Data Scientist, and every few weeks, I've to present my work to small/large audience. It can be 5-10 people to few hundred people. My trick is to prepare the topic inside out, and account for all possible questions, so I won't get caught off-guard. Usually I spend part of my weekends preparing for the presentation. One thing that helped me was the realization that stuttering is ok as long as I get my point across. Sometimes, to ease my mind, I might start a presentation with voluntary stuttering "sssssooo, my name is pppppi..." Most people in the company know by now that I stutter (even though I never mentioned it explicitly). It doesn't seem to bother anyone though. If i do get caught with unexpected question/argument, then my stuttering might get severe. This has happened few times, but I've learnt to brush them aside after the incident.