Referenced

I can pick a lock or repair a watch.  I can conduct surgeries, examine corpses for forensic evidence, bind a book, dress a deer, identify or concoct poisons, and reproduce Lord Nelson's flagship down to the last knot and nail.  If necessary, I can also conduct a Latin Mass, reproduce the scripts of Carolingian scribes, shoe a horse, summon Cthulhu, or swear like a WWII soldier.  I can walk the streets of forgotten cities in lost kingdoms and navigate the alleys of Calcutta in the year 2010.  And I can do it all from the safety and convenience of my writing chair.

Some of these things I can do because I'm weird that way.  For the rest of it, I have reference books.

If there are any writers who don't have a personal library of research materials, I haven't met them yet.  If you want to be a writer, I swear that the first order of business is to nail down a handy and reliable source of research material.  Whether it's a colonnaded building built with a Carnegie grant or an impressive list of websites and online journals or a room in your house (apartment, condo, whatever) an eccentric collection of research materials grows as a result of the curiosity that made you become a writer in the first place

I never studied medicine but one of my main characters in the last novel I wrote was an MD.  I could go online, of course, and get a lot of information and some of it would even be accurate.  But far better for me to be able to reach over and pulling my Manual of Surgery or PDR, or Mosby's Manual of Diagnostic Tests off the shelf and getting on with the writing.

For most writers I know, research is our drug of choice.  Putting a slumgullion of random yet curiously interrelated websites and blogs at my fingertips just ups the danger of losing my workday down the rabbit hole.  I can spend hours hopping from topic to topic, following a chain of links down a questionable path of lies and truth spun together into a strange blend that even William Gibson's Neuromancer failed to adequately predict.  How easy it is to get lost on the information superhighway, tumbling in the slipstream of bits and bytes as I bounce from website to website, digging up one quirky fact after another like a hyperactive two year old shoveling candy into his mouth.

Far better to bind my search between boards.  Paper is safer and there are no pop-up ads or viruses.

Your public library is a good start and will always and forever supplement your home library.  In fact, the aspiring writer needs to first and foremost make friends with the reference librarians at their local branch library.  A first name basis is best, and you might even want to learn how to bake their favorite cookie because odds are good that you're going to put their library sciences degree to work.  You're going to be the story they tell around the supper table that night when they get home; embrace the fact. 

"So that writer guy Scott came in again today and asked me to help him calculate the amount of whalebone harvested by Basque whaling fleets before 1610."   The answer is approximately 24 million pieces.  Academic libraries are the best and if it wasn't for the able assistance of Becky, Kendall and Rachel, I would never have discovered the various academic journals that allowed me to piece that together.

Which reminds me.  I need to bake some snickerdoodles.

Even straight literature requires at least a modicum of research.  One story idea I'm developing would feature nary a single mysterious element or unexplained death.  But it still required me to pick up an old pocket watch repair manual and another on the history of the American athletic shoe industry.  In any story, for any market, it is the job of the writer to create the verisimilitude of background and character that allows you to accept the setting and concentrate on the story.  Unless you are an acknowledged expert in every field your writing will touch on or uncommonly skilled at lying... you're going to need some help at some point.

I'm not suggesting that you have to become a Crichton or Clancy, but it's important to get stuff right or know how to lie convincingly.  I swear that half of fiction writing is getting a feel for when you have to know what you're talking about and when I can make stuff up.  (Yes, we lie to you all the time; the sign overhead in the bookstore says 'fiction' for a reason.)

My dad taught me that a personal library largely exists to supplement the public libraries I frequent.  Duplicate books you want to collect, but save your money if you're not filling the gaps.  It has since grown to encompass books that I reference often enough that I don't want need to get in the car to go consult them.  My dad wasn't a writer, but it's worth noting that at his funeral, the local librarians were among the mourners.

"I like books. I was born and bred among them, and have the easy feeling, when I get in their presence, that a stable-boy has among horses."

- Oliver Wendell Holmes

Buy the books you need to touch more than once a  week.  The collection will grow of its own accord, so devote some space to the books you love and the books you need.  Cicero said that to add a library to your home was to give it a soul.   Your relationships with your books and those who purvey them will extend that feeling to your words, imbuing them with soul as well.