Ken, you will get lots of different ideas, but the number one thing is to do what works for you, in your area.
If you don't track your results, start now. I try to make it a practice to ask each customer where they found me and to be as specific as possible.

Traditional Yellow pages are pretty much dead in my area,IMHO since I am in a high tech area.
I know I get a dozen or more books that go straight to the recycle bin when they arrive. I always search on-line when I need anything.
I have always had a yellow pages ad or two in the small town I started in but had few results.
When I relocated to the Dallas, TX area, I bought yellow page ads again and then tracked it.
I did not get ONE inspection for the entire year.
I then switched to yellow pages on-line with moderately better results.
I think everyone will agree the best you can hope for is to be in the top 5 for organic search results in popular search engines, but that takes time and I am still working on it. I am forced to do the pay-per-click through yahoo and google.
The best bang for the buck has probably been my vehicle signage.
Good luck!

__________________
Jim Luttrall
Mr. Inspector.net, Inc.
Allen, Texas 75002