On Website Articles:
Earn with Referrals
How to get the most images approved.
About PayPal.
Each websites FAQ.

Off Website Articles: (opens external link, in new window)
10 Reasons Why Your Stock Photographs Are Rejected
Reasons for Refusals (Photodesign)
Eight Secrets from the World’s Top Selling Photographer
Getting Started on iStock
The Background and Foreground in Portraits
Stock Photography: Shooting Concepts
A Good Stock Image is an Incomplete One…