ok, we all understand that keywords can not be general? as targeted as you can. Break keywords up into ad groups and write 2 ads per group, get rid of the low performer and then right another ad until you have your gains are minimal - but what makes a good affiliate ad? for specific products I like putting the product and price in the ad. If you are selling a Sony Vaio xxxx laptop and you say
Sony Vaio XXXX
Fantastic laptop for$xxxx
free shipping or $xx off
or something to that effect you are going to discourage more browsers and lookyloos! Any one want to expand? also your display url should be product related, I have found it to help. There is alot more to writing ads but this is the basic idea....