Concerning the Gundam franchise, timelines, and watching order:

Because there is no overlap in the Gundam timelines, there isn’t a specific viewing order for the timelines.  Also, series of the same timeline can be considered separate entities, and knowledge of events that took place in its predecessors isn’t strictly necessary for understanding the events that occur in the later series.  Movies, which are more or less simply extensions of the main series anyway, are obviously exempt from this and watching them before having seen the series is just stupid and you should probably just stop.  The ones I’d suggest starting with, to their respective timelines, have been italicised.

Universal Century (U. C.)

• Mobile Suit Gundam MS IGLOO: The Hidden One Year War (January, U.C. 0079)
• Mobile Suit Gundam MS IGLOO 2: The Gravity Front (U. C. 0079)
• Mobile Suit Gundam MS IGLOO: Apocalypse 0079 (U. C. 0079)
• Mobile Suit Gundam: The 08^th MS Team (October, U.C. 0079)
• Mobile Suit Gundam (September, U.C. 0079 – 80)
• Mobile Suit Gundam: The Origin (September, U.C. 0079 – 80)
• Mobile Suit Gundam 0080: War in the Pocket (December, U.C. 0079 – 80)
• Mobile Suit Gundam 0083: Stardust Memory (U. C. 0083)
• Gundam Neo Experience 0087: Green Divers (U. C. 0087)
• Mobile Suit Zeta Gundam (U. C. 0087 – 88)
• Mobile Suit Gundam ZZ (U. C. 0088 – 89)
• Mobile Suit Gundam: Char’s Counterattack (U. C. 0093)
• Mobile Suit Gundam Unicorn (U. C. 0096)
• Mobile Suit Gundam F91 (U. C. 0123)
• Mobile Suit Victory Gundam (U. C. 0153)
• G-Saviour (U. C. 0223)

Future Century (F. C.)

• Mobile Suit G Gundam (F. C. 60)

After Colony (A. C.)

• Mobile Suit Gundam Wing (A. C. 195)
• Mobile Suit Gundam Wing: Endless Waltz (A. C. 196)
• Mobile Suit Gundam Wing: Endless Waltz The Movie(A. C. 196)

After War (A. W.)

• After War Gundam X (A. W. 0015)

Cosmic Era (C. E.)

• Mobile Suit Gundam SEED (C. E. 71)
• Mobile Suit Gundam SEED C. E. 73: STARGAZER (C. E. 73)
• Mobile Suit Gundam SEED Destiny (C. E. 73)

Anno Domini (A. D.)

• Model Suit Gunpla Builders (A. D. 2010)
• Mobile Suit Gundam 00 (A. D. 2307)
• Mobile Suit Gundam 00 Season 2 (A. D. 2311)
• Mobile Suit Gundam 00 The Movie: A Wakening of the Trailblazer (A. D. 2312)

Advanced Generation (A. G.)                                            

• Mobile Suit Gundam AGE (A. G. 115)

Gundam Production Order

1979

• Mobile Suit Gundam

1981

• Mobile Suit Gundam I
• Mobile Suit Gundam II: Soldiers of Sorrow
• Mobile Suit Gundam III: Encounters in Space

1985

• Mobile Suit Zeta Gundam

1986

• Mobile Suit Gundam ZZ

1988

• Mobile Suit Gundam: Char’s Counter Attack
• Mobile Suit SD Gundam Mk I

1989

• All That Gundam
• Mobile Suit Gundam 0080: War in the Pocket
• Mobile Suit SD Gundam MK II
• Mobile Suit SD Gundam MK III
• Mobile Suit SD Gundam’s Counterattack

1990

• Mobile Suit SD Gundam MK IV
• Mobile Suit SD Gundam MK V

1991

• Mobile Suit SD Gundam Musha Knight Commando
• Mobile Suit Gundam 0083: Stardust Memory
• Mobile Suit Gundam F91

1992

• Mobile Suit Gundam 0083: The Fading Light of Zeon

1993

• Mobile Suit SD Gundam Festival
• Mobile Suit Victory Gundam

1994

• Mobile Fighter G Gundam

1996

• After War Gundam X
• Mobile Suit Gundam Wing
• Mobile Suit Gundam Wing: Operation Meteor I
• Mobile Suit Gundam Wing: Operation Meteor II
• Mobile Suit Gundam Wing: Operation Meteor III
• Mobile Suit Gundam: More Information on the Universal Century
• Mobile Suit Gundam: The 08^th MS Team

1997

• Mobile Suit Gundam Wing: Endless Waltz

1998

• Gundam Mission to the Rise
• Mobile Suit Gundam: The 08^th MS Team – Miller’s Report
• Mobile Suit Gundam Wing: Endless Waltz Movie

1999

• Turn A Gundam

2000

• G-Saviour

2001

• Gundam Neo Experience 087: Green Divers
• Gundam Evolve (2001-2007)

2002

• Mobile Suit Gundam SEED
• Turn A Gundam I: Earth Light
• Turn A Gundam II: Moonlight Butterfly

2004 

• Superior Defender Gundam Force
• Mobile Suit Gundam MS IGLOO: The Hidden One Year War
• Kimi ga Nozomu Eien: Gundam Parody
• Mobile Suit Gundam SEED Destiny
• Mobile Suit Gundam SEED MSV Astray
• Mobile Suit Gundam SEED: Special Edition
• Mobile Suit Gundam SEED: After-Phase Between the Stars 

2005

• Mobile Suit Gundam SEED Destiny Final Plus: The Chosen Future
• Mobile Suit Zeta Gundam: A New Translation – Heir to the Stars
• Mobile Suit Zeta Gundam: A New Translation II – Lovers

 2006

• Mobile Suit Gundam MS IGLOO: Apocalypse 0079
• Mobile Suit Gundam SEED C.E. 73: Stargazer
• Mobile Suit Gundam SEED Destiny: Special Edition
• Mobile Suit Zeta Gundam: A New Translation III – Love Is the Pulse of the Stars

2007

• Mobile Suit Gundam 00
• Mobile Suit Gundam SEED: Super Nova – Tanekyara Gekijo

 2008

• Mobile Suit Gundam 00 Season 2
• Mobile Suit Gundam MS IGLOO 2: Gravity of the Battlefront

 2009

• Mobile Suit Gundam ZZ: Gundam Frag
• Ring of Gundam

 2010

• Model Suit Gunpla Builders Beginning G
• Mobile Suit Gundam 00 The Movie: A Wakening of the Trailblazer
• Mobile Suit Gundam SEED: The Movie
• Mobile Suit Gundam Unicorn

2011

• Mobile Suit Gundam AGE

2012

• Mobile Suit Gundam: The Origin