Externalize often. The more you express those ideas—in words, in sketches, in prototypes, in demos—the more visible those flaws will be to you and other people. There’s a reason that Leonardo da Vinci kept a notebook in which he sketched and wrote every idea he had: it allowed him to see those ideas, share those ideas, critique those ideas, and improve those ideas. Had he kept them all in his head, his limited capacity to see and reason about those ideas would have greatly limited his productivity.
I agree becasue I believe that it is easy to think of a vague, rough idea idea in your mind; but to perfect, visualize and externalize it is another thing. If we hesitate to record our idea right away, there is a good chance we will lose it. For a instance, when I start a essay, I found making a outline that lists all my thoughts would be helpful. I am sure it will be helpful to all of us if even Leonardo is doing it.