I am not a professional guy at all. I just have a passion for detailing and do it on the weekend for extra cash. I developed a really, really nice descriptive three page flier. I used a nice font, one neat little graphic and had a professional copy editor (my best friend's wife!) review and edit it for content. I had the senior designer at my job look it over for cosmetic layout purposes. I bought really nice quality stationery at Staples (on sale) and had them laser printed on it with matching envelopes. I had adresses printed on labels and put on the envelopes. I created a nice vehicle inspection report as well.
I mailed it to 50 of my parent's friends who live near by. I mailed to all my neighbors on my block. I mailed to all my personal friends and some of their friends that I know.
As a result, I have a whole bunch of cars lined up to do. When neighbors see the cars, when friends of my friends and my parent's friends see the car, the word spreads. They also see my flier and they are impressed further.
That's how I do it. Direct marketing to people I know with a professional looking product. This leads to word of mouth. I don't advertise on billboards or pass fliers under people's winshield etc...
In fact, my neighbor (whose white Acura I did) has a close friend who has a warehouse of 12 cars he wants me to look at! That'll keep me busy (if I get it) for many summer weekends!