I do lots of 1-2 hour presentations.
- Do not read slides. Summarize them in your own words.
- once you see the new slide, you should barely have to look at it or refer to it as you present that content
- Use plenty of graphics, decoration is fine so long as it is relevant
- Vary the slide layout, lists, tables, word clouds, charts, diagrams
- use graphical representations of as much as possible, diagrams are very valuable
- stop every couple of slides for questions
- define the goal of each section before starting
- I prefer they not have copies of the slides in hand, too much browsing
- go faster than you think you should. Tendency is to dwell and go slow. Generally will waste time and bore.
- practice the presentation in real time out loud at least twice, for timing. Write (or have someone) the elapsed time after every three or so slides so you can see if you are on pace.
- try to get questions every half-period or period. Have one typical questions ready for you to ask and answer to seed them.
- have food and drinks available, easy on the sugar, heavy on the caffeine
- be animated and excited about the content. Smile a lot. Joke a little. Look into your audience's eyes directly.
- The other suggestions here sound great, too.
Good luck