There's SO many stories of works that are now considered timeless classics that were rejected dozens and dozens of times. If you're unsure about your abilities yes, having someone else read over it is a good idea, to help with any technical issues, but even technically poor work gets published--so much of it has more to do with timing and connections than raw ability. I said in the rejection therapy thread that I volunteer for a small pub and see firsthand how sometimes really great pieces get turned down for no fault of their own; sometimes a pub is just full, or sometimes it's a great piece but we already accepted something similar, or it's just not as on theme as a slightly less good piece... there's so many factors that have absolutely nothing to do with your ability or the piece's quality.