A valuable tool that can help you succeed in half the time would be Keyword Spy which is a fantastic spy tool for affiliate marketers.
You can see what adverts and keywords other affiliates are actually using. You can simply steal their keywords, re-write the advert and your good to go. It even shows you which program the affiliate is using and if your a clickbank affiliate it even provides you with the programs hoplink to the landing page.
Just imagine how much time this would save you on ad testing and choosing the best keywords. You can simply see the best keywords that have proven conversions and add them straight into your adwords account.
The best affiliates to spy on would be the ones who have a few products and a low keyword count. This would help you more as the affiliate may have started out with 1000 keywords for a campaign and after he has tested the keywords he may only have around 50, so watch out for these affiliates as these keywords will have been selected due to high conversions.
Keyword spy will even show you the Return on Investment for each keyword, the affiliates advert position and how many competitors there are on google for the keyword.
Enjoy and Succeed.