I was cruising around and found a Yahoo coupon and took their service for a run. It worked about the same as Google and since it only cost me $5 for a $50 credit so no matter what you cannot go wrong. Cruise around and find a coupon and give it a test run.
Here is a nice little vid explaining some search marketing, the only true kind.
I recently did an Adwords that worked pretty well. I broke just above even. Well i made 25% on my investment so i guess it worked. I will continue to use them for my online stores and see how well it goes.