Never stop testing, and your advertising will never stop improving.
David Ogilvy (1911–1999) US “Father of Advertising”
Turn the notebook screen to you. Thus, you don’t have to turn around and see what is actually shown on the screen.
Test your presentation! First of all check to see if all the slides are in the right order, that your animations (if you use them) are working properly and that the presentation works on the computer system you are going to use.
Second, test it for the timings, intonations and possible questions / misunderstandings together with another person. Go through the whole presentation as if it were the real thing. Steve Jobs, the Apple CEO, used to rehearse for 48 hours with a selected audience. If you don’t have anyone nowadays Smartphones are useful helpers: film yourself and review yourself critically.
Test your presentation as well as your technical settings. Watch also out for the No-go-Area!
Third, testing of the technical equipment (cable connections, batteries, settings of computer in connection with data projector etc.) is also crucial. Don’t forget to schedule this time (and forget that many participants show up earlier and you won’t have the time to fix technical things when they arrive).
Fourth, watch out for the No-go-area, i.e. where you shouldn’t stand or walk in order not to block the audience’s view on the screen.
The use of colors helps to orientate your audience. Be consistent. It might lead to confusion if you aren't. Always use same colors for the same purpose.
Layout helps the reader to understand and navigate through the structure. Layout is orientation. If the structure is unclear, you yourself are unclear.
First of all nobody says that a presentation has to be by data projector. But if so, nobody says it has to be with PowerPoint; there can be better options.