Some time ago I was asked, “How do you know when something you’ve written is ‘good enough’?”
Without knowing where a writer is in his or her journey, that answer is almost impossible. However, here’s a quick breakdown:
1) New writers are likely going to need quite a bit of advice and polishing and even re-polishing of their work before it’s ready for publication. Period. (See my article “Write It Again, Sam” for nagging reiteration of this.)
2) More experienced writers might not need lots of “going over” but a crit group or friend or two to pick at their work is still a good idea.
3) When you feel it’s as best as you can get it (you’re down to twiddling over minutia, like which is the best adjective for a sentence – because perfectionists like me can always find some little thing to pick at), then submit it. If it’s accepted, fine. If not, look it over, with your crit group if you can, and try to find out what’s wrong. Could be lots. Or it could be fine, and the editor just didn’t like it.
4) What works for one writer might not work for another, so find what works for you.
5) Don’t sweat it.
6) Keep writing!