Use appropriate font styles
Avoid using more than two type styles on a banner. The more fonts used, the harder it is to read. You should limit your banner to two styles of fonts
Use Graphics Appropriately
Logos, clip art, borders, etc. can effectively be used to grab the viewer's attention, but should not overpower the sign's main message .You do not want the viewer to only concentrate on the cool clip art or graphic, if they do then your message may be lost.
Consider viewing distance and viewing time
For example, if a grand opening banner will be on the front of a business with a large parking lot between the storefront and the street, the letter height must be large enough to be viewed by drivers on the street. You need to realize that the average driver only has about 1.5 - 3 seconds to read a message while in motion.
Use effective color combinations
Create your banner with a combination of colours that have a high contrast between the background and letters This makes your banner easier to read and can be viewed from greater distances.
Although these are good general guidelines, they might not always produce desired visual results. You need to work with your sign company to create an attractive and effective banner. This will ensure your banner will be not only seen but read and that your message will be communicated with the desired effect.