I have tried both Google and Yahoo as well as a few other less known
it seems my best clients come from forum or free ad postings.
Remember the cat
give him a ball of yarn he'll play with it forever. Buy him something from the store he wont touch it.
It seems that Google all I did was spend money. but I didnt spend a lot
I have found a site called http://www.spyfu.com
it pretty much tells you how much other sites have spent on google etc.... and unles you spend around $1 or $2K on them your business will get off to a slow start.
I found that Godaddy spent about $700 in one day. I dont have that kinda money to check and see how things go.