Color is relatively easy. Length is not. Long hair to me might seem like medium length hair to you. Try to describe it so someone else can visualize it. Sometimes it's better to describe it as looking like someone that most everybody has seen.
Facial hair is next.
Clean shaven or unshaven. Forget about eye color, you probably can't remember it and the cops can't see eye color from the patrol car anyway. Now to complete a quick description, you'll need to provide the information on what he is wearing. Again, from the top down. Now his shirt or jacket.