The production order of Legend of the Galactic Heroes for prospective viewers:

Legend of the Galactic Heroes: My Conquest is the Sea of Stars (1988)

This is the prequel movie, however, it isn’t necessary to watch before the 110 episode OVA.  I’d suggest watching it if you’re uncertain as to whether or not you’d be interested in LoGH; it gives a fairly good idea of LoGH’s pacing, and introduces a few of the main characters.

 
Legend of the Galactic Heroes (1988-1997)

The main OVA, 110 episodes, the bulk of Legend of the Galactic Heroes, and where magic happens.

 
Legend of the Galactic Heroes: Golden Wings (1992)

A prequel movie.  I’ve yet to watch this.

Legend of the Galactic Heroes: Overture to a New War Movie (1993)

This is essentially the first couple episodes of the main OVA made into a movie with additional scenes.  A fantastic introduction to the series, establishes main characters, setting, and now available in 1080p (!).

Legend of the Galactic Heroes: A Hundred Billion Stars, A Hundred Billion Lights (1998-2000)

Takes place before the OVA but is meant to be watched after its completion.  24 episodes following Junior Admiral Reinhard von Musel and his ascension in the Galactic Empire’s chain of command.

Legend of the Galactic Heroes: Spiral Labyrinth (1999-2001) 

Same as above, 28 episodes, more Yang Wenli-based.

My suggested viewing order:

1. Legend of the Glactic Heroes: My Conquest is the Sea of Stars
2. Legend of the Galactic Heroes: Overture to a New War
3. Legend of the Galactic Heroes
4. Legend of the Galactic Heroes: A Hundred Billion Stars, A Hundred Billion Lights
5. Legend of the Galactic Heroes: Spiral Labyrinth
6. Legend of the Galactic Heroes: Golden Wings (?)