Below is a short and simple list of techniques which you should keep in mind when creating banner advertisements. Many studies have been compiled which prove the usefulness of these techniques and others like them.
Add words promting the visitor to take action. Perhaps the most common example is "Click Here". Words such as "Free" will also grab the visitors attention.
Create a sence of urgency, prompting the user to click now. "Hurry! only while stocks last" is an example.
Use animation to draw attention to your banners.
Keep your banners simple, don't try to give the viewer too much information. It is the banners job to get the visitor to click on it. It is the web sites job to provide them with information.
Create a colour scheme and style for your banner. Make sure you keep it constant throughout the banner, especially when using animation. However, you must be careful. Make sure your key words such as "Free" and "Click Here" stand out.
Create banners which look interactive. Add buttons, and other objects visitors are familiar with clicking on. I am sure you have all seen banner adds which simulate the windows environment.
Target your audience. Make sure the content and layout of the banner will be appealing to your target audience.