How far must a man go in search of himself?
Fact and Fiction
Historical Research and Detail

In my case, I wanted to write about a Civil War soldier in the Battle of the Wilderness. I was particularly interested in the Wilderness because of the difficulty of waging a battle on such awful ground, and because, in my view, the Wilderness signified the actual turning point of the conflict--the time and place at which Union tactics changed and eventually brought about an end to the war. When I got home, I carefully catalogued my information and then I started doing research online. Since I wanted to include scenes about battlefield medicine, I located web pages in that regard. I found experts who maintain collections of Civil War surgical instruments. And I bought more books. I also found entire books posted online and available: old journals, diaries, and medical books; battle plans and battle reports; and I found REENACTORS! These hard working keepers of history possess incredible amounts of information on all aspects of the period. From them, I gained information and source materials about everything from fabrics to architecture. I printed out reams of information and catalogued it all in looseleaf binders. NOTE: Set your printer properties to the lowest resolution and black and white print if you're going to do this. You can also save all these things to disk, of course, but it's so much more convenient for me to be able to lay a binder open and read the material while I work, as opposed to hopping from one computer window to another. Feeling very sure of myself, I began recounting to him the story I'd heard back in Virginia, about how the Union had used chain shot to take down the trees on the Wilderness Battlefield. Well, he looked at me like I had snakes crawling out of my nose and then proceeded to pull out book after book, and showed me that there was, in fact, no documented land use of chain shot during the entire war. There are advertisements in periodicals that do not exist elsewhere. They describe medical prpocedures, foods, books, clothing--virtually every aspect of society. There are also advertisements for various clubs and organizations; there are essays on a variety of subjects. But don't just rely on Harper's Weekly. You can easily access newspaper archives from all over the country, and many of them are online. Large cities are your best best. Photographs from the period are especially plentiful. Photography was a new science and photographers trooped right out on the battlefield where they took some of the most heartwrenching photographs in history. Be particularly observant when you look at period photos, especially those that are 'unstaged'. You'll discover ways people wore their clothing, their hairstyles; how they stood, what their homes looked like, and you might even catch details about attitude, in general.
I'm a huge worrier! Whenever I write history, I worry that I don't include enough historical material, or that I put in too much. I worry that readers of narrative non-fiction will find my stories too 'character driven'. Conversely, I worry that readers of historical fiction will find my stories too dry. But in spite of the fact that this constant internal dialogue goes on, in the long run I think it's a good thing. It drives me to be as accurate as I can be when including historical information. And it keeps at me to tell the best story that's in me.
There are those who say, "It's only fiction. Who cares whether it's accurate or not?"
I care.
I care because I think it's important to convey not only a sense of place in the writing, but an honest picture of the times. If honesty isn't paramount, then why write historical fiction at all? Why not just write fantasy and call it what it is? Beyond that, I think readers of historical fiction want to read what's factual, but long for that reality to be staged within the confines of a story so engaging that the two entities--fact and fiction--meld into an unforgettable literary journey.
It's my fervent hope that my own writing both informs and entertains. To me, that's the true test of quality historical fiction.
So, where does one begin?
Start by deciding what story you want to tell. You'll be surprised, though, how much that story will change when you begin your research; my stories do, anyway. But even though you know things are going to change, get the original idea for your tale down on paper. That doesn't mean you have to write the entire book; just jot down a brief outline or synopsis. That's enough to keep you on track. 
I got the basics of my story down and then traveled to Virginia to visit the places about which I intended to write. I went to Fredricksburg and Wilderness. I made contacts at the National Park Service. I identified recognized 'experts' on the Wilderness and the Civil War, in general, and I bought their books (isn't that what every author does--buy books). I also visited countless other CW battlefields: Chancellorsville, Spotsylvania, Cold Harbor, Appomattox, Gettysburg, and many others. While visiting these places I took notes and took photos. I jotted down ideas based on the stories I heard told.
I found 19th century etymologies and slang dictionaries. I found slave dictionaries and information on the writing of dialects.
As with all research, the first rule of thumb is to NEVER trust your only source. A perfect example of that is my own experience with a type of Civil War ordnance called 'chain shot'. When I was back at Wilderness, I was told by someone there (another tourist, I'm sure) that the Union had used chain shot to take down the trees and clear portions of the battlefield there. I jotted that down, thinking it might make an interesting tidbit in my novel.
Back here in the West, I had occasion to travel to Denver, Colorado to the Colorado Gun Collectors' Association Show at the Merchandise Mart. It was there I found a preeminent collector and historian regarding Civil War saddles and other accoutremont. But it was also there that I found another man who put me on the trail of the truth about chain shot. He was displaying a large array of Civil War maritime artifacts, including an example of chain shot. His display told how chain shot was designed and used to take down masts on opposing navy's ships.
Needless to say, its use isn't in my novel. I was embarrassed, of course, but much less so than I would have been had I written a scene that more knowledgeable people than I later called me on.
So, thus far we have several resources in our research kit: location, written historical records, experts, and the internet.
What else is there?
There are artifacts--actual items that were in use during the period: patent medicine bottles, clothing, furniture, militaria, buildings, conveyances--the list goes on and on. Two extremely valid resources are newspapers and music/art of the period. Harper's Weekly, printed for decades, can be found in large bound volumes (yes, I own one). In it are actual reprints of the newspaper as it was printed 150 years ago. Not only can one read news about the war as it happened, one can develop a sense of the society of the times, get a feel for the language/syntax of the period, and gain insight into society's side-issues. 
Music, as with all other art forms, also provides insight into the period. And, of course, Civil War period music is a fascinating study into American culture. Both the North and South produced music prolifically, and music also grew out of slave culture and out of the many other ethnic groups that were part of the strata of American life. Wondering where to find Civil War period music? Start with the hymnal at church. You'll find dozens of songs written during the period 1861-65. As with almost every conflict, the longer it lasts, the more readily the population and the military turn to faith for solace.
Another fabulous resource is the US Government. The National Archives and Smithsoniam Institute are second to none when it comes to the accumulation, cataloguing, and sharing of information. Photos at the National Archives--both in person and online--are identified as to whether they are part of a collection to which one must apply for copyright permission to use, or whether they are 'public domain', which means one is free to use them for web pages or in printed material.
Other quasi-governmental sources are college and university collections. VMI (Virginia Military Institute) maintains a huge Civil War collection, as does the University of Virginia. The historians at the United States Military Academy at West Point are also very helpful and forthcoming. Virtually every city in America is burgeoning with museums, and every museum has a historian or curator, and they all love to share.
Historians, after all, are not in the business of keeping all this information SECRET. They love what they do and they are happy to share. Can you imagine being privy to the past and not having anyone with which to share the information?
Remember, several hundred words back when I mentioned that my story changed based on the research I did? Well, it sure did--and that new story required new research. I learned in my reading that thousands upon thousands of the disenfranchised and disillusioned left the East and headed west after the war--and so did my characters. So I had to find sources for research materials about the West. My favorite turned out to be the Wyoming State Archives, but historical societies and museums are excellent as well.
It doesn't matter what you're writing about, there is someone out there who is an expert in its regard--probably many someones. The fact of the matter is that writing good historical fiction hinges in large part on those who have already accumulated information.
If you're afraid to approach people to pick their brains; if you hesitate to ask questions; if you're just too shy to query those who clearly have not only a wealth of knowledge to share but an enthusiasm for their subject matter, then perhaps you need to rethink your desire to write.
Otherwise, when you do approach people, do use their information, and do go on to find other sources, don't forget to say thanks.
That, and keeping your facts straight are the most important things.