personally i just read the short story collection Jesus' Son by Denis Johnson and i absolutely recommend it. the stories are short and snappy (the whole thing is less than 200 pages) and follow a single narrator who is never named and calls himself/is to referred to by his friends as "Fuckhead." basically the narrator and his friends are all drug addicts and the stories are just random things he has been through/experienced as a result of being high all the time. Johnson's style is awesome. the narrator is incredibly detached and distant from his whole life and just weird, but the overall effect of this works wonderfully well.
i also like Thomas Pynchon's voice/style a lot. it's really difficult (i'll admit, i tried reading gravity's rainbow, gave up after the first 200 pages), but even just reading a little of his work definitely left an impression on me.
all time favorites? Hemingway. anything Hemingway. particularly The Sun Also Rises or A Farewell to Arms for novels. "Snows of Kilimanjaro" for short stories.
I think reading poetry is incredibly helpful, even if you are mostly interested in prose. some of my personal favorites are Robert Hass, e.e. Cummings, T.S. Eliot, Stephen Dunn, Albert Goldbarth, and Wallace Stevens
