I have now completed the first 5 Dune books and am currently starting the sixth, Chapter House Dune. After that I will read Hunters of Dune and Sandworms of Dune to complete the main series, then I will read the Legends of Dune series, The Butlerian Jihad, The Machine Crusade and The Battle of Corrin, followed by the Prelude to Dune series, House Atreides, House Harkonnen and House Corrino and finally start the Heroes of Dune series, Paul of Dune and The Winds of Dune, the latter being the most recent.