Last night my SF writing class resumed at Writers & Books. For seven of the eight weeks of each term, this is a critique class, but the first week we get organized and then do some sort of exercise. Last night we had critiquing practice by attacking an old, unpublished, very bad story of mine. I wrote this thing thirty years ago, before I had any idea what I was doing, as in: What is a point of view and why is it nice to have one? When I say "very bad," it's not false humility. The class slashed away merrily.
But afterwards I got to thinking: How much do you have to write to take yourself from bad amateur to pro? Of course it varies with the writer (I understand that Robert Silverberg sold his first story). But is there some sort of average? Fred Pohl wrote that it takes a half million words to become good, but that seems high to me.
More interestingly, what can the aspiring writer do to shorten that apprenticeship? Only two things occur to me. First, get reliable feedback, which my students are doing, -- or at least I fervently hope that's what's happening in class week after week. Second, read a lot of SF or fantasy or whatever you're hoping to write. Too many of them, alas, are not doing that.