Good point but how do I reach someone like yourself If I'm the new kid on the block trying to reach a broader clientel*
You say you have a good customer base. Offer existing customers a discount for referrals, with a discount for the referred customer also. It may not be the quickest way to grow, but if your work is good, those customers will be with you for life.
For some generalities, just present a professional appearance with your logo, colors, and literature. It would pay to have a professional design something, or at least run it by a bunch of people like us. I don't know graphic design. I can't come up with anything, but I know what good design, and crap design look like when I see it.
I guess what I'm saying is you have to look expensive, whether you are or aren't. Low budget promotional material gives the impression of a fly by night hack. Quality materials and lay out give the feel of permanence, and confidence that you'll be there to take of them well into the future.
Edit:
To more directly answer your question, I still use the phone book when looking for services I'm not intimately familiar with. Block ads that are professionally laid out, but not too extravagant are what I look for. That says to me the company does good work, but isn't super extravagant, and charges a fortune to pay for their advertising budget.
Edit2:
For an idea of what I mean by "too nice" a layout, think Geek Squad, or a store front martial arts school(Kims Karate if they're still around). These kinds of places have the budget, but not the skills to perform the necessary task. I look for an ad that says "small but skilled" when I'm shopping for a service.