Here I go repeating myself.
No matter how small your business, and how little marketing you do, you can have consistency in your items and materials.
This is a basic, a fundamental. Make everything look the same, no matter how simple it is.
Do you have letterhead, business cards, any sort of signage (even if only a magnetic car sign)? Do you have a website, a simple brochure? Is there a message on your voicemail or telephone system on-hold?
ALL of these MUST look the same.
If not, you are automatically wasting a large portion of your marketing efforts.
Period.