I learned a bit about publishing and the printed book while working at Addison-Wesley Publishing Company as General Manager of their Educational Software Division. Back in those days of yore software actually shipped with user manuals, so I had to deal with layout, typesetting, printing, etc. How quaint!
But there’s one technique from print that I do recommend you borrow for your presentations, though this piece of advice is aimed at ventures who are far enough along to have a product to show, or at least a prototype. The screenshot above was taken from an Apple presentation about a new version of the Apple TV.
While you may not have a giant screen behind you like this presenter (whose all black outfit merges with the image) you can still use the technique of call outs to help viewers understand your product. You can think of a call out as a special type of image caption. Instead of captioning the entire image a callout calls your attention to a specific part of the image, in the case above, to the numerous output on an Apple TV.
You can get really fancy and use the build function of PowerPoint or KeyNote to progressively add new captions to the same image.
With all due respect to Apple, kings of the keynote, I wouldn’t put a black product image on a black background, nor would I have the presenter dress all in black. Very funereal! Make sure your product or prototype image stands out against the slide background and that your callouts are big enough to read and clearly attached by fine lines to the features you are trying to highlight.