Are you targeting the right customers? (4 criteria)
Is your customer insanely, irrationally passionate?
Are they great in number? (High-traffic sites or barring that, low traffic niche websites).
Are they easy to reach? (High keyword response, easy to identify, frequent similar places...)
And lastly - Would you want to hang out with them.... forever? (How else can you target them) *
Seems like a good set of ideas to hope for when you're setting up a campaign!
Thought I'd share. Jason