Create a custom color palette. You may not have your logo on the slides, but you can still incorporate your brand into your presentation material. Create a color palette based on your logo or on a photo representative of your industry. My favorite tool for this is Kuler. Just upload an image and let Kuler do its thing. You can tell it whether you want bold, colorful, or subdued colors.
Write down the RGB values for each color. You can enter those values into PowerPoint's color picker when selecting color for text, shapes, or lines. These will then show up as choices the next time you need to change a color. I create a color palette slide at the end of the deck to use as reference while creating the presentation. An example of this is below.
Once you have a palette use it in a consistent way for text, shapes, charts, etc.
Use Grids to create a flexible, yet consistent layout. In Slide:ology, Nancy Duarte recommends using grids to maintain consistency in the placing of elements from one slide to the next. Check out Adam's example of a 4 x 4 grid system. Try a 5 x 5 grid or 4 x 5 grid. A 3 x 3 grid is great for using to the rule of thirds. Here is an example of a Fibonacci grid with the color swatches for a corporate color palette.
|From Jeromy Timmer|
Use photographs. People remember pictures better than words. This is called the picture superiority effect. In addition, people remember concepts better when they hear about it and see it (but reading does not count as seeing). Since this is a live presentation, you have the hearing part covered. Use pictures and images to reinforce the
The clip art built into MS Office is overused and cliched. Avoid it. Instead, use professional looking photographs from stock image sites such as iStockPhoto.com or Flickr. You can find very creative and striking images from the stock photo sites. But if you need shots of people exhibiting genuine emotion you'll have better luck with Flickr Creative Commons photos.
Use fewer words. As a rule: If you are going to say it, then it does not to be on the slide. This will keep you from reading the slide, which bores the audience to death and reduces comprehension. Use keywords and headlines for the audience to key in on. But avoid complete sentences (other than the headline, or pertinent quotes).
Those tips will get you started toward better looking presentations. for more advice on Presentation design read the following.
Speaking about Presenting