Don't let too many ideas, themes, or words convolute the entire advertisement. Three to five words within a space of 20'x20' works best. Size is key to the content of the sign. You probably don't want to mix too many media, too many colors, or too many textures. Think in terms of the visual communication process.
Attraction is the most important step in the process.
To attract, the attention of the consumer must be seized-and held. Once someone notices the sign, part of this process is achieved. However, the concern is with getting the attention of the targeted customer. This is when strategy decisions can get tricky. Ploys such as quirky cartoons, bright lights, or loud colors can interrupt the gaze of any passerby.