Short fiction is the medium I love the most, because it requires that I bring everything I've learned about poetry - the concision, the ability to say something as vividly as possible - but also the ability to create a narrative that, though lacking a novel's length, satisfies the reader.
I love learning about different dialects and I own all sorts of regional and time-period slang dictionaries. I often browse through relevant ones while writing a story. I also read a lot of diaries and oral histories.