In August 2011, NPR released the results of a poll to list the top 100 science fiction and fantasy novels. It's a great list, but not much guidance as to where to start. SF Signal came to the rescue with a handy infographic that uses a flowchart to choose which book to read. Click to enlarge:
http://www.sfsignal.com/archives/2011/09/flowchart_for_navigating_nprs_top_100_sff_books/