I was reading one of the Guerilla Marketing books (great books by the way), and it said that you need to make sure you have your customer service right before you use any great marketing tactics; otherwise you will only speed up the demise of your business.
I saw a great example of this on a trip to the beach. A small ice cream stand had sent a girl (about 10 years old) out to pass out coupons for a free ice cream cone. This was truly Guerilla Marketing, and it seemed to be working.