Make sure you maintain a consistent graphical language throughout your slides. Here is a thumbnail view of a section of a deck I used in recent meetings.
Here are the guidelines I used:
- Dark background, white text, purple accent
- Page-filling, black and white images
- No capitals
- Selectively bolding a word in a sentence
- No slide titles in a fixed position
Every slide blends right in without, complicated graphics, and SlideMagic makes it really easy to apply this style.