Yellow Pages
The "real" Yellow Pages
Get in the Yellow Pages. This is a no-brainer. Whoever calls themselves the "real" Yellow Pages in your area is where you need to be. The yellow pages are where the majority of people still turn to find a business.
Yes, it is expensive. If you can only put money into one thing, put it here.
The "Other" Yellow Pages
Advertising in the secondary yellow page directories is great as well and if you can afford it, be in all of them. Ususally the secondary directories are cheaper than the "real" one.
Some marketing gurus will tell you to hold out until the last minute to see if the advertiser will throw in a color or bold listing for free and that is a tactic that sometimes works. Regardless of how you negotiate, be IN the very next issue.