The other day, someone asked me if I ever read novels as part of my research, and my answer was, "Yes." I know some writers would throw up their hands in horror, because there's always the spectre of accidental plagiarism, or the suspicion that you'd possibly end up writing more like the novelist than yourself. But I read lots of books all the time, of all kinds - it's when you stick to one author that problems like that can arise.
So why would I research by reading fiction? The same reason I watch movies. The atmosphere. The setting. A good writer takes me into their imaginary world (even if it's based on fact - which most historical fiction is) and helps me to imagine my characters in a similar world. For me, it's another version of actually going to that place. I was lucky to be able to go to South and North Carolina this year to do more research for my novel, Pirate X (due out in 2011).The trouble was that much of the coastline is now filled with houses and tourist developments, but it still helped when I found an isolated area to imagine it all looked like that once.
However, I wasn't able to go to Nassau, and I'm sure it looks nothing like it did in 1717 when it was a pirate hangout, filled with tatty tents, garbage and empty bottles! However, I did get hold of an old copy of James A. Michener's Caribbean, and skimmed parts of that for a sense of place. I did the same with sailing ships by reading some of C.S. Forester and Patrick O'Brian, and watching the Hornblower series and Master and Commander. I also crawled all over the Endeavour replica ship in Darling Harbour, Sydney.
Some time ago, as part of my research for a completely different story, I tracked down a copy of The Scourge of God by William Dietrich, which is about the Romans and Attilla the Hun. The level of detail and description in this book is astounding, and when I later visited Toulouse, it gave a whole new resonance to what I saw in the museums there. Historical fiction for me began (as it did for many readers my age) with Georgette Heyer, Mary Renault and Anya Seton, among others, but books like Dietrich's go far beyond these in terms of historical detail. I often read something that leads me into new research, and books with good bibliographies are even better.
Authors like Dietrich and O'Brian also remind me that surface research never works - that there's always more to discover, if you persevere. Occasionally Wikipedia has led me to something useful (usually if the entry has a good bibliography), but more and more I'm going back to books as my best source of the kind of in-depth information I need. What I'm finding the internet useful for now is images! I use old photos and images and maps a lot, and these can be both easier to find (thanks to library collections) and more valuable for things such as finding an image of a character.
Currently I'm working on the Australian Girl series, and I now have a collection of old photos I've printed out of children around 1900. In those, I have at least three characters - when you know your character really well, you can look at photos and think, Yes, that's Abigail. She doesn't usually look that tidy, but I think her mother made her dress up for this! It's a lot of fun to do it this way.