There are more different paths to publication than there are works that have been published. So it's difficult to say anything that is universally useful.
Here are a couple of truisms that hold most of the time:
- Writers write. No-one has extra time in the day just handed to them by a benevolent deity, designated for the sole purpose of writing. If you yourself don't prioritize writing and set aside time for it in your busy schedule, it's not going to happen.
If you trust in yourself. . .and believe in your dreams. . .and follow your star. . . you'll still get beaten by people who spent their time working hard and learning things and weren't so lazy. - Terry Pratchett
(I think most of the time, at least for me, it's not laziness as much as it is intimidation. While the story is just a dream, it is perfect. Every word I commit to brings it further down to grubby imperfect reality. But none of those words has to be a lifetime commitment. Once the story is written out, I can go back and improve it. For me (and many others) the secret of good writing is re-writing. Read Anne Lamott's 2 pages on "Shitty First Drafts"; then just dive in and begin writing your first draft.)
- Editors select works on the basis of lots of different criteria. A perfectly good poem or story might not fit into their current vision. That doesn't mean it's not good. It doesn't mean that another editor wont buy it. Just find another market and submit it there. There are authors who have amused themselves by papering walls with their rejection notes. I think that was more interesting when the rejection notes had more substance. Most of the ones that I have received have been form letters "thank you for submitting your work... we do not have the staff to give individualized feedback... we cannot use this story at this time..." I do try to keep track of who has rejected a story, so that I don't accidentally send it back to someone who has already said "no." I don't want to be a pest.
Think of the last time you were excited about a new book coming out in a series you love.