I have the movies listed here in chronological order of the story, rather than order of release. (Side stories, aka "anthology" films, have an asterisk.) This doesn't mean to suggest I think you should necessarily watch them in that order. The actual order in which the (main) movies were made goes: Episode IV, V, VI, I, II, III, VII, VIII, IX. Actually, my personal recommendation is to watch them in release order, except with Clone Wars between episodes II and III. You could also try Machete Order, but I've never done that, so I can't comment on it (except to say that it sounds interesting).

Also I should say that this is one of the most massively popular franchises in the history of modern storytelling. It has had an incalculable influence on other sci-fi stories that have come after it, and on pop culture in general. It has generated countless merchandise. There have been numerous parodies, fan films, commercials, homages, rip-offs, discussions about the movies by fictional characters in other movies or shows, etc. Here are just a few of my favorites:

Clerks / Fanboys / The Force Awakens from Its Nap / George Lucas in Love / Hardware Wars / Laugh It Up, Fuzzball / Phineas & Ferb / The Pink Five Saga / Spaceballs / Space Janitors

prequels era:
Episode I: The Phandom Menace
Episode II: Attack of the Clones
* The Clone Wars
Episode III: Revenge of the Sith

original trilogy era:
* Solo: A Star Wars Story
* Rogue One: A Star Wars Story
Episode IV: A New Hope
Episode V: The Empire Strikes Back
Episode VI: Return of the Jedi

sequels era:
Episode VII: The Force Awakens
Episode VIII: The Last Jedi
Episode IX: The Rise of Skywalker