i was paying a professional to do my adwords campaign, then decided to look into doing it myself, bought a great book and read it, had a look at the professionals campaign and it was a complete joke. anyone can say they are an expert at adwords and if you haven't got a clue then you'll believe them. after reading the book i got someelse in to do a new campaign and guess what, they were a joke as well. first carpet cleaning campaign they did went straight to my home page when it should of gone straight to my carpet cleaning page. sacked them as well.
my advice, buy a book on adwords, watch a few videos, and then either do it yourself or get someone in to do it but at least if you do the latter, you know what questions to ask and you can pop in and check on the campaign as its being built.
Adwords is actually relatively easy to do, i'm now doing my own campaigns, building them slowly and right. and actually enjoying it.