Research is something you need to do before you write, but it's also very important after you've written. If you want to take your writing further, by being published, you need to learn about the industry you're getting into.
If you're interested in pursuing traditional publication then research the agents or publishers you want to submit to. Find out which authors and novels they already represent/publish, find out what they're looking for. Follow them on social media, look at their website or blog and ALWAYS READ AND FOLLOW THE SUBMISSION GUIDELINES. That one is important enough to deserve all caps, trust me.
If you want to go down the self-publishing route, find out the different options that are available for print and digital publishing. Join forums, chat to people who have already been there and find out about their experiences. Look into the best ways to market your book without annoying everyone with constant spam - "You can buy my book here!" "Look at this review for my book!" "Here's another link to my book, and my Facebook page, and my Goodreads page!" - I see far too much of this on Twitter, and it has not yet persuaded me to buy a book. I buy from authors who interact.
But I digress. When I first started submitting work to agents, I didn't have a clue what I was doing, because I hadn't spent long enough researching the query process. My submission itself was awful and unprofessional, I didn't really know what genre my novel fitted into, so I'm not surprised I was rejected. Now that I know a lot more about the industry, I am confident that my next submissions will be a lot smarter, clearer and more professional. I can't guarantee I'll get an agent, but I've got a lot more chance than I did a few years ago.
Research takes time but, like editing, it's worth it. Better to spend a few weeks really getting to grips with what traditional or self-publishing is really about than to leap in blindly. The more you know, the more chance you have of being successful.