Jeremy Gordon: A Completely Subjective Do’s and Don'ts Guide to Freelancing
This is from a freelancer writer, not a web developer, but most of the principles still apply.
• DO: Wake up early
• DO: Cultivate multiple interests so you are widely hirable
• DO: Build a good network of friends doing the same thing as you
• DO: Read the comments and grow a thick skin (I don't know about this one…)
• DO: Respect your editor
• DO: Stand up for yourself; the people who hire you are not right by default
• DO: Ask for your money
• DO: Buy business cards
• DO: Be positive and supportive
• DON'T: Push yourself to do too much or something you're not ready for
• DON'T: Read the comments (enough to build confidence, then never again)
• DON'T: Pitch stories to your friends who are editors, it'll make it weird
• DON'T: Be jealous