1. A New Hope (episode IV, the one people mean when you say “Star Wars”)
  2. The Empire Strikes Back (episode V)
  3. Attack of the Clones (episode II)
  4. Revenge of the Sith (episode III)
  5. Return of the Jedi (episode VI).

“Basically you have the original trilogy with a big two-film flashback at the cliffhanger at the end of Empire. And no Phantom Menace at all.” http://www.thevine.com.au/entertainment/movies/the-right-way-to-watch-star-wars-20130115-259271