Does the message create maximum visibility? Use colors and pictures to contrast with the sky and other surroundings. Is the ad readable from various distances, angles, lighting and weather conditions? Your creative design should be specific to the board if possible or if not then designed for the poorest visibility board in the showing. Are you saying only one simple key statement? Nothing else will be read and may endanger the more important messages. Do not put words or sentences stacked on top of each other. This reduces the ability to understand and view the message. Less is more. Does your ad have a sufficient amount of space between the actual lines and words? If the letters or words run together it won't be read.