So, once you have your mansucript done, revised, proofed, ready for publication... what do you do?
You send away your manuscript to a Big Publisher, and think it will succeed or fail on its own merits.
Getting published by a large publisher, unless your name is already well-known, is a completely randomized process. Michael Allen reveals how manuscripts are REALLY selected (or not), in his tell-all book On the Survival of Rats in the Slush Pile.
It's recommended reading for writers. Honestly, I didn't think the state of Big Corporate Publishing was THIS bad -- until I read Allen's book. I learned several useful lessons:
1. "Nobody knows anything." Modern Big Publishing is a complete lottery, and the odds are stacked against writers.
2. The best way to keep a cool head is to write what YOU enjoy writing, and not write for money/fame. (Or write for your friends and family.)
3. Ignore Big Publishers. No, really. S****'em. Find a small publisher that's willing to publish your work at a low cost (read: low financial risk) and nurture your talent over time.
(If, against near-impossible odds, you SHOULD get a deal with a Big Publisher, you are s****d. Because the Big Publisher will give you one chance to sell humongously well with your first published novel... and if you don't, they'll toss you aside like a used Kleenex. You don't get to hear about this a lot, because people tend to ignore all the writers who bombed, and focus on the spectacular successes.)