I like Revenue magazine.
http://www.revenuetoday.com/

Shawn Collins has a good Blog. http://www.affiliatetip.com/blog/
I’m still looking for other good blogs but they are rare.

http://www.abestweb.com/
This is the best affiliate forum. (IMO) If you lurk and post long enough you’ll eventually learn some of the best angles as well as who the subject matter experts are that are generous with sharing information.

It’s best in my opinion to focus on an industry you have some knowledge of and work those programs first.

Many of the affiliate programs you join will send newsletters with helpful tips and tricks for better placement of banners and links.

However it’s best to visit the conferences etc. It’s a bit like SES where people you have met posting on aBestWeb.com will have a few beers and start telling you where the real opportunities are that they wouldn’t normally post. Everyone has an angle. Learning SEO (and buying the book) ;^)is always a good first step.

The best free resource I know of is Allan Gardyne's Associate Programs site:

http://www.associateprograms.com/

The thing about affiliates is that they can be a substantial source of revenue, but recruiting is a marketing project in and of itself. We have customized our affiliate script so that affiliates can actually personalize the affiliate pages. Even with this feature recruiting affiliates has been a hurdle.

-Randy
www.4mysales.com

Around a year ago I found via TW http://affiliateclassroom.com/magazine.php and read some good bytes. Probably has evolved since then.