Visuals will keep the audience's attention better if you use a variety of type fonts and sizes. Memorizing a speech isn't a good idea. Each visual should include no more than two key concepts. Casually leaning back on one hip tells an audience that you're less formal and thus more believable. To get an audience to think creatively, project information on the right side of a screen.
Audiences react better to consistency, so use no more than one or two fonts.
Also, it's best to use a sans serif because it's easier to read in the larger sizes you need for the screen. True, but some experts recommend that you memorize the first minute or two to help you build confidence by starting strong. Limit each visual to only one key concept or risk confusing an audience with too much to recall at once. It signals non-verbally that you wish you didn't have to be there. Research also shows that you should put the image or the words as high on the screen as you can get them.