Problems are not stop signs, they are guidelines.
Always desire to learn something useful.
If you're going through hell, keep going.
Expect problems and eat them for breakfast.
It's always too early to quit.
Be kind whenever possible. It is always possible.
If you can dream it, you can do it.
If you've got a talent, protect it.
Never complain and never explain.
Do not weep do not wax indignant. Understand.
There's obviously nothing wrong with selling your art - only an idiot with a trust fund would tell you otherwise. But it's confusing to know how far you should take it.