You do your research. You learn the basics and mechanics of writing. You write a terrible novel. You learn from it. You write a pretty good novel. Maybe you even write a stellar one.
You do more research. You learn how to craft a query letter. You figure out which literary agents represent the kind of work you're producing and you send them that query letter. You personalize your queries and you follow all directions to the letter.
At this point, you've more or less exhausted the what portion of your knowledge.
To be fair, this filters out a substantial number of people: you'd be surprised how many queries (or attempts at queries) agents receive from people who (1) are functionally illiterate, (2) know nothing about the publishing industry or how it works, (3) are crazy, (4) are unable to follow directions, (5) haven't actually finished the novel they're pitching, &c &c. You're reading this blog, though, so chances are slim that any of these apply to you.
The number of people trying to sell a novel these days, however, is so unimaginably huge that even with all the hacks and lunatics filtered out, you're still facing long odds. Knowing what can only get you halfway there, if that. Now you've got to know who.
Caveat: thousands of writers are discovered/find representation every year without knowing a soul in the industry. They've never attended a conference, workshop, or seminar in their lives; they're just truly fantastic writers who found agents with whom their work resonates. The odds of this, alas, are astronomical. You should, à mon avis, endeavor to improve them.
Maybe you have a great relationship with a professor and she offers to show your short stories to her agent; maybe your best friend has an agent and he thinks your work would interest her, too; maybe your uncle's former roommate is an agent and your uncle offers to hook you up; maybe an agent you pitched your novel to at that conference last month wants to see a full MS.
The possibilities are endless, and when you aren't writing or reading, you should be thinking about networking: specifically, think of people you know who can help you further your career. No one sells their book solo; take the time to cultivate relationships that can get your foot in the door down the road, and your odds of one day seeing your book in (e)print will rise more than you might think.