First, there’s the definition of “good.”
Art and entertainment are completely subjective. Beauty is in the eye of the beholder. While there are certain standards by which many of us agree to judge worthiness, it’s still not even close to being objective. Organizations routinely give awards to books that would bore the heck out of most readers. Meanwhile, other groups give awards to books that the literary types deem “trash.” All kinds of books become bestsellers—from the most intelligent, scholarly masterpieces to more easily accessible stories that attract readers for reasons other than literary excellence.
The question is, what kind of “good” are you shooting for? The “good” that wins literary awards and gets starred reviews in PW? The “good” that attracts readers and leaves them wanting more of your work? Some combination?
Whatever the answer, you’re shooting for a murky target. You won’t find a solid working definition of “good.”
Second, what kind of validation are you looking for?
The question above said, “how do you validate that what you are doing is good?” We’re all looking for validation, but your task is to try and understand what YOU will find validating. A few friends loving your work? An agent taking you on? A major publisher signing you? Or maybe none of those things will happen but you’ll self-publish. Can validation come in the form of thousands of copies sold and lots of positive reviews from readers? You might not know until you’re further along this journey and have some experience with different avenues of getting your work out there.
But let’s get back to the crux of the question: How do you know if your work is any good—by anybody’s standards?