"Don't be afraid to make ugly paintings" That is the best art instruction advice you will have hear. Too many artists are hesitant to really "go for it" slap paint on the canvas, swirl it, stab at it, scrape it or wipe it off. The last 100 years of art making has proven that art is often beautiful if it is also challenging. This should give us all the freedom from inhibitions to make "acceptable" art. Wild and free we can make ugly paintings and not look over our shoulders.
But in the end, we need to be free of the idea our art may ever be acceptable. It just needs to be acceptable to us. And that will make all the difference.