Don't give up, even if your story or novel gets rejected. It's easy to become disillusioned when you send something to an editor and it comes back with a note saying: "Thanks, but no thanks." Try to view this merely as one of the necessary steps on your journey to becoming a writer (I know this isn't easy, but it's essential in order to move on). I've met too many aspiring writers who have shown huge potential, but who give up writing after receiving a couple of rejection letters.
So, my advice is 'never give up'. It is the writers who are persistent that go on to be successful.