The correct order is the order in which they were released:

1977 - Star Wars (aka Star Wars Episode IV: A New Hope)
1978 - The Star Wars Holiday Special
1980 - Star Wars Episode V: The Empire Strikes Back
1983 - Star Wars Episode VI: Return of the Jedi
1984 - The Ewok Adventure (aka Caravan of Courage)
1985 - Star Wars: Ewoks (Season 1)
1985 - Star Wars: Droids
1985 - Ewoks: The Battle for Endor
1986 - Droids: The Great Heep
1986 - Star Wars: Ewoks (Season 2)
1999 - Star Wars Episode I: The Phantom Menace
2002 - Star Wars Episode II: Attack of the Clones
2003 - Star Wars: Clone Wars (Seasons 1 and 2, DVD Volume One)
2005 - Star Wars: Clone Wars (Season 3, DVD Volume Two)
2005 - Star Wars Episode III: Revenge of the Sith
2008 - Star Wars: The Clone Wars (Theatrical Film)
2008-Present - Star Wars: The Clone Wars (TV Series)

Personally, I'd just stop at 1983, while also skipping 1978, but that's just me.

If you're already a fan, then hey, go ahead and watch them in any order you want. But any chronological order just would not work for anyone who's never seen any Star Wars.