BTW, I'm not sure I understand why you think it's so important to present with a Powerpoint (or similar). I tend to think Powerpoints get overused, and I often like to present working just from notes (3x5 cards, since I'm bad at memorizing) or from a demo when appropriate.
What's the win of working with a deck, in your view?
IMO, a good presentation with whatever-you-call-the-visuals is more difficult to do well, therefore that's what I think you should practice.
Speeches and demos are always easier to give. They may be more appropriate for certain subjects, no doubt.
- Add structure in a visual way.
- Provide graphics to illustrate your points (including code).
...and really that's about it. I keep my slides to one graphic or max five words, plus a little flow chart of progress through the presentation along the bottom. Depending on what I am talking about I might use as many as 2 slides a minute, but usually one every 2-3 minutes.
This is the same for monthly reporting (twenty graphs, with a page number on each) through to conference speaking (scripted and learned, lots of pictures, little navigation helper on each page).
Stacked up, they looked a little like a deck of cards, thus the nickname "deck." You can probably find one (and someone old enough to remember when they were called decks) in a museum somewhere.