I think it might be easier to figure out what you do want by figuring out what you don’t want.
You don’t want to say the same old thing. You don’t want do a repeat of something that sold , because then you are just looking for the elusive secret that the first painting had. Maybe there is only one thing and you can’t just crank them out .
Being inauthentic is another avoid-at-all-costs trap , so we don’t want to go there.
As long as you know what to avoid, you can see what you do want. Real. Refreshing. Beautiful and surprising work. I think the work has to surprise you too. There is no formula and if you have one then throw it out. Formula art is not even art.
What you are left with is best-case scenario , authentic, egoless, courageous art that speaks to you and everyone else — something that was never heard before. This is every artist’s best; it’s the reason to keep painting because when you do this — when this occurs — it is actually fulfilling your destiny.