I will list things to be careful of on this page. Just to start out with I'll list TrafficPower as a place to stay away from.

TrafficPower.com:
Back in the day I ignored what I consider a wee bit of common sense and fell for one of their cold calling fast talking salesmen. I have learned enough since then to make one of their sales people run in the other direction. In short they had a lot of customers that they got banned from Google. In fact TrafficPower itself got delisted out of Google and yet they claimed to me and others that they would get good rankings for our businesses in google an other search engines. The only thing they could get to rank are obscure keywords that no one really searches for.