WHAT ARE THE RULES?
I have only one rule: BE NEAT
If you do neat work, you can do anything else you want, and it doesn’t have to be perfect or look like anything in particular to be wonderful!
(Later on I will post the principles and elements of design, with examples. It is good to understand what they are in case you feel "stuck" in your art. Reviewing them will nearly always give you ideas on how to improve your artwork.)