I have pondered the advertising route. I chose not to, simply to keep it a part time hobby. For now i choose to only take in word of mouth customers. If i was to advertise i would use all low or no cost avenues that would allow me to accomplish two things. Get my information out to those who need it and seperate myself from other detailing busines's. Facebook is great at showcasing your previous work, before and after pictures, happy customer testimonials, services offered, and contact information. Business cards are great to put in the hands of happy customers who will hopefully pass them along to new clients. Use both. They are very low cost advertisement and both have benifits. Once your business has grown then an .com can be added for a more permenent presence. Your website can go even deeper into your business with scheduling and pricing. There are plenty of cheap startup website companies out there that help with formatting and layout.