Basic Rules of the Freelancer

I've been reading a lot of articles lately about freelancing and how to succeed at whatever type of freelance work you do. No matter what type of freelance business you run, there seems to be a set of basic rules that will set the foundation of your business and will keep it going strong. The following are a few of the Freelance Rules to Live By. Feel free to add your own in the comments section.

1. Don't Be Afraid To Say No. This applies to everything from not overworking yourself to not bending your artistic integrity. While I wouldn't suggest anyone say "NO!" right away, especially when first starting off as a freelancer, I would say that this rule has a lot of merit. All of the books warn against being a freelance workaholic, working 18 hours a day in your tiny hole of a home office. Turning down a few jobs just to keep your sanity -- and relationships -- in check is definitely something you need to do. However, if your client (the one who pays you) needs you to make a few corrections or make some changes to the project you have completed, I would go light on the nos and flex your compromising muscles.
   
2. For the love of God, never miss a deadline! There is no quicker way to fail as a freelancer than to miss a deadline. Even if your mom goes face first into her bowl of crab bisque and you stub your toe on the way to the funeral home, those excuses won't matter to the guy 1,000 miles away who needs your promotional materials lest he lose his job. Deadlines, deadlines, deadlines!
   
3. Part of being a good freelancer is being a good business person. It's important that you keep records, pay your taxes, and buy your licenses and permits. Join the Small Business Association of your town (and maybe even the town next to yours) and network like a pro. Send Christmas cards to clients, take people out to eat, buy people drinks. It's all tax deductible, so why not?
   
4. Take some time every week and improve your skills. Many large corporations require their employees to improve their knowledge and skills before being promoted. Why should your business be any different? Take some time and take an art class, go to a lecture, or read a book. Do something completely unrelated to your business. Take a cooking class if you're a writer. Take Yoga if you are a videographer. Believe me, it'll help. There is no such thing as a wasted experience.
   
5. Have fun! The most important thing about being a freelancer is to have fun. We don't go into business for ourselves to hate our jobs and constantly wish for something more. Do little things that add up to make working for yourself a real pleasure. Play your iTunes really loudly, work in your underpants, post pictures of Angeline Jolie all around. I personally drink wine while I work. I maybe go through a glass a day. While not much, it helps set the mood for my office and greases up the old creative gears and gets things flowing.

I would be interested in your rules of being a successful freelancer. Comment with your tips, and I will update at a later time.