Took a course on public speaking
As a first-time speaker at iOSCon 2019, I was required to take a two-day workshop on conference speaking given by SkillsMatter. It was quite honestly the best piece of professional development I have done so far. Especially as someone who was so nervous about speaking, the workshop really made me feel a lot more comfortable. It even made me completely re-think my talk! I... might have re-written it the night before I gave it.

The idea of the workshop was to give a five-minute lightning talk on a topic of our choice. We went through the process of determining our audience, writing an abstract, crafting a message, putting slides together, and actually presenting. We gave our talk at the end of the first day and then again at the end of the second day. The difference was remarkable.

I would include a link to the class, but they don't offer it anymore.