PointRoll hands out nifty little notebooks with the first page filled with Best Practices for Display Banners.  Here's a summary:

1.  Keep the campaign objective and key metrics in mind when designing banners.   Use more than one panel for displaying a lot of info or you want user interaction and engagement.  If direct response is desired, one action-focused panel is most effective.

2.  Banner animation should not be too slow or too fast; the call to action should appear immediately.

3.  Give the user a compelling reason to rollover with a clear, prominent, and relative call to action.

4.  Rollover hot spots should be as large as possible and easy to see.  On most sites, the rollover max spec is 33% of the banner.

5.  All panels should be accessible from any other panel.  Use horizontal hot spots on horizontal ads and vertical hot spots on vertical skyscraper ads.

6.  Ideally, the entire panel should be clickable, and also use a well-defined click button.

7.  Include a "loading" message that appears as the video streams in.  Users with slower connections will know the video is coming.

8.  Use video player controls for optimum usability - pause, play, and volume.

9.  Video should auto play upon user rollover.  Requiring users to "click to play" reduces video plays.

10. After video completes, include compelling, relevant call to action.

More Best Practices for display banner ads are listed at http://www.pointroll.com/best-practices.aspx.

Definition 6 can help you craft your online advertising strategy, whether it is banner ads, organic or paid search, or email marketing.  We negotiate with vendors to maximize your media spend when developing Media Plans that meet your objectives.  We design and build ads and deploy them, working with partners, such as, the search engines and PointRoll.  We do it all!