Mostly, getting published is a no-brainer:
Create a quality product the market(s) want to purchase.
Well, yeah, not so much.
What does quality really mean, especially when it comes to writing?
First--you have to know what you see as quality. I know many new writers get sucked into the life of an aspiring author. They read the works of other aspiring authors in an attempt to exchange critiques and hone their craft. This is a great way to learn to self-edit as well--what you can point out needs work in another person's writing might help you see similar errors in your own.
Aspiring authors usually go through a reading drought--because they are so focused on learning the craft, their critical eye gets in the way of their enjoyment. They see sentences that wouldn't make it through round one of the critique group, or past their creative writing teacher or mentor. Or, they find themselves taking notes on how an author managed to accomplish something they're struggling with.
(The above passes, by the way, so if you're trapped in reader limbo and feeling agitated about missing something you enjoyed immensely, know that this is merely a phase that you're moving through, not staying in.)
So what does the above have to do with judging the quality of a written work?
If your bookshelves are filled with decades old novels, or worse, empty, then you're subjecting yourself to an uphill battle in a career that is already bloody and brutal.
Make it habit to seek out newer releases that are highly popular in the field you write in. Don't worry about it informing your writing. Of course it will, as does everything you do and live. You'll not accidentally begin writing like Dean Koontz or James Patterson--that's not possible. Your voice will always shine through.
In these tough economic times, the library is always an excellent resource. Often they'll have new releases to "rent" in hardcover before the paperback even comes out. Find a way, but get those novels read!
Nothing can replace the first-hand experience of reading a book the market is devouring currently. Once you get about six or seven of these under your belt, you'll begin to see the difference between what you write, what your aspiring friends write, and what is getting published.
Of course learning the craft is an ongoing process. I'm still learning, and will still be learning for the rest of my life. I tend not to take on new projects unless there's a challenge for me in the work--that's what drives my passion--wanting to make every story bigger and better than the one that came before.
Once you begin to discover what your challenges are by reading how the experts handle them (how does Anne Rice write such descriptions? How did Stephanie Meyer work her magic? How does James Patterson or Dean Koontz make science so entertaining? What makes Cussler's Dirk Pitt someone you always want to read about?) you'll be on the right track to creating your own brand of quality product for the market.
If you want to get published, then you need to be an avid reader.
Then of course comes self-discipline and learning to be prolific, but in those glorious developing years where you're free to write what you want, linger where you need to, and explore to your heart's content, take the time to find out what type of quality you're interested in creating--and then practice and practice some more.
Once you have that quality product, you'll need a quality advertising pitch to the publishing house or agent of your dreams. This includes a query letter that'll knock their socks off, and a synopsis that shares just how exciting the plot, characters and writing is in your novel. Making industry friends through attending conferences and such is another great way to get your completed quality product in front of the right people.
I hope this helps and if you have any questions, please feel free to ask in the blog and I'll answer as best as I can!