If you were put-off by the sheer bulk of The Savage Detectives or 2666, one of his shorter works provides an ideal starting place. My recommendation for the uninitiated (or those who wish to delve deeper into Bolano's universe) would be to pick up his collection Last Evenings on Earth. The stories comprising this volume contain all of the themes of his later work - an obsession with poetry; madness and violence; casual love (with anything but casual consequences); literary feuding; and a brooding melancholy hanging over every action or inaction. The difference between these stories and Bolano's larger works rests in their concision and their heightened sense of power.
Not much happens in a Bolano story: a narrator (often Bolano's alter ego Arturo Belano or simply B.) travels, bumps into people, drinks in seedy bars, reads books of minor poets. The plot doesn't drive the stories, it's a vision of the world, the transformation of the ordinary into the extraordinary: a crystallization of vision.