There’s a great article at alzado.org. I actually advise you to read the whole article because the points below are just the most important for me.

1. Look up for good customers, the ones that pay well.

2. Ideas, Ideas, Ideas. Charge for your ideas, for your content and art design.

3. A great design starts with great content.

4. A good design lasts forever

5. A good design is for everyone

6. You must be a master even if you don’t execute it.D

7. Share your ideas.

8. A good design is the one that pays good.

9. Don’t work with with if there’s money involved

10. Copy all the good things you can get your hands into

Source: Criterion