The banner ad serving system Adform provides a very clear description of the industri standars covering display ads. The specifications can be found here.
Adform also provides a service that will check that your banners adhere to the specifications and limitations describes. You can test your banners here.
Average CTR for display advertising: 0,1%
1. Stop effect
The elusive mysterious forever wanted Stop effect. What makes the viewer focus on your banner. The viewer didnt come for your banner, so your banner must be interesting enough to distract the viewers steal the attention.
2. Banner placement – Physical and in the conversion pipeline
When Kottler wrote Marketing Management, one of the points was that you allways need to create the demand in ýour advertising. The only place you could skip that, and only provide the solution, was in the phone book / yellow pages. If someone where looking up plumbers in the yellow pages, they probably allready had a plumbing problem.
However with todays Behavioral Targeting….
3. Call to action on as large a part of the banner as possible.
No need to have the viewer wait to perform the action you want him to. If he is ready on slide 2, why have him wait for the “Do it” button on slide 5.
4. Every “slide” must make sense.
You never know when the viewer suddently pays attention to your banner, so no matter when the viewer “enters” he must be caught and retained. A long series of uncoherrent arguments will send the viewer straight on to the next eye catcher.