This not all that easy for me, as I'm not all that big on rules, particularly when it comes to design and work, but here are a few I've thought about:
1. Dress like you're going to work, even if you work from home
Don't underestimate the power of costumes.
2. Don't disguise bad work with style
I've only ever heard minimalism used to justify a lack of content and concept
3. Never stick to a personal style.
Allow others to write your wikipedia page.
4. Failure is fine
So long as you've got a roof, bed and full belly.
5. Bury yourself in your work
It's like swimming, you'll only know if you like it if you dive in.
6. Sunlight
I'm not sure if it helps or hurts my focus.
7. Remember Parkinson's Law
Work expands to fill the time available for its completion. Get a job, get some proper hobbies.