Hi,
I'm thinking of starting an AdWords campaign, but before I begin can anyone tell me what the biggest problems are with AdWords or what I should watch out for?
Thanks,
Humsmasher
Google officially HATES all affiliates and will do everything they can to make your life harder. There are much easier ways to get traffic at scale than Google. Expect to have to hustle your ass off just to tread water, especially if you're asking this question.
Well if Google sees an affiliate ID they will ban you and send a notice to your bank which will freeze your bank account and decline most of your credit cards. You can read more info here http://www.google.com/faqs/affiliate-sabotage
Make sure you focus on your CTR. Higher CTR = better QS = cheaper clicks. Always be testing different ads (use A/B Split Testing Calculator to test to statistical significance).
Make sure your keywords are grouped really tightly.
Make sure your landing pages are as targeted to your adgroups as possible.
Once you do all this, and Google still fucks your QS, you'll understand why there is so much hate for them here.