The best artists delete their own weak work before anyone sees it. Be your first critic.

Everyone produces a lot that is not good, including the people whose output looks flawless. The difference is what happens next: they cut theirs, and you only ever meet the survivors. Editing yourself is not harshness, it is the ordinary part of the job that nobody sees. It also protects the good work, since a weak piece next to a strong one drags the strong one down.

Before you post or hand in a set of things, take the weakest one out. Not rewritten, just removed. Do that every time and the level of what people see from you rises without you getting any better.