Star Wars: Choosing Music: Future Proof Version

Here's the future-proof version, with all links followed by track names and references in case the videos vanish.

I like having music for my story games. It's a handy way to set the tone. For an Apocalypse World game I made hour long tracks of rain and wind mixed with static, screaming, and distorted music (Tom Waits, Godspeed You! Black Emperor, some Chinese pop tunes, etc.). For my Rogue Trader games I've got playlists of over-the-top nonsense. Cathedral-starships require it.
Here's how I picked music for a Star Wars game. It might be useful if you've ever wanted to have a game with a soundtrack but weren't sure where to begin.

The Official Scores

You don't need an ultra-high fidelity edition, but you'll probably want all the movies. Buy them, rip them, and start listening track by track. Try to get a feel for what makes music "Star Wars"-y. Listen for leitmotifs or theme.

Every character gets a leitmotif in the movies. Darth Vader (Imperial March) 00:12-00:37). Leia (Leia's Theme) (00:00-00:55). Rey (Rey's Theme) (00:00-00:22). Notice how short these lietmotifs are, and how each one has a distinct feel? You'll hear them throughout the soundtracks.

If you want to learn more about leitmotifs, the great* scholar Anna Russel does an excellent lecture on Wagner's Ring cycle. (Anna Russel, Ring cycle) It's surprisingly helpful, and I'd love to see a Star Wars version one day.

*in a very technical sense of the word.

Anyway, there are some leitmotifs that just won't work in your game. Vader's theme is probably the main one. Unless your game contains Darth Vader, it's probably best to skip the Imperial March completely.

Sorting

Take all the tracks you think you can use and rename them. I used the format "Category - Description - Length". "Kylo Ren Arrives at Battle" becomes "Imperial - Turbulent - 2m02s". "The Asteroid Field" becomes "Space - Chase - 4m15s" The names let you immediately select a track based on what's going on in your game. The categories I used are: battle, filler, force, imperial, intro, leitmotif, outro, space, urban.

You will need to use a program like audacity to split a few tracks. That "Space - Chase" track needs to lose the first 50 seconds of the Imperial March. Audacity is ridiculously easy to use. It'll take no time at all.

New Tracks

There are a few rules for Star Wars-y music.
1. No singing. There are only a few piece with voices. "Duel of he Fates" and "The Emperor's Theme" (the start of the Klan rally in O Brother Where Art Though, where they're all marching and chanting) No, wait, that's not the Emperor's Theme. (Gregorian chants) That's not it either. Here we go.  (The Emperor's Theme) If you're going to use pieces with voices, make sure it's for a really good reason.

2. No chorus. Williams repeats himself, but not in a way you could chant or dance to. This immediately eliminates a huge swath of music. This piece (Bach, Suite #2 in B minor, rondeau) wouldn't work for Star Wars. This piece (Prokofiev, Dance of the Knights) would. And this (Uaxuctum, Giancito Scelsi) is going too far.

3. No pianos or electric guitars or bells. If you there are drums in the piece, they compliment the main theme but are never part of it. Huge booming drums aren't used.

This is the most time-consuming part of assembling your music library. Start with soundtracks to other films. Don't be afraid to be picky.

Look for pieces that have a strong "voice" - an instrument that dominates the piece, supported by other instruments. Look for violins, oboes, flutes, and trumpets. Avoid deep bass rumbles. Most Star Wars music is surprisingly light in that sense.

Leitmotifs

You should also consider building some leitmotifs for your characters from non-Star Wars tracks and playing them during pivotal scenes. I can't offer much guidance here. Try to pick a short (1 minute or less) bit of music that has a single dominant instrument. If you're able to find multiple tracks with the same theme (from a film soundtrack, for example), you're golden.

Examples from my game. Apologies in advance.
The lonely pilot who dreams of adventure. 
Flute Solo, Lucky Number Slevin Soundtrack
The same pilot, in a militant mood.
Epic Goodkat, Lucky Number Slevin Soundtrack

The bounty hunter and his ancient and powerful family.
The Force Unleashed, General Kota and the Control Room
The bounty hunter confronts his destiny.
Earth, Space Battleship Yamato (2010) SoundtrackBecause that my game would have a Western theme, and was full of scummy and villainous characters, I broke my ban on guitars for leitmotifs only.

The murderous protocol droid in a calm and reflective mood.
Sister Sara's Theme, Morricone
The stories the protocol droid tells of his past.
Circular Story, The Man from UNCLE (2015) Soundtrack

Consider giving your game a theme as well. I start every major story arc with the main theme and a custom crawl, but immediately afterwards, I cut to this bit of music while describing the opening scene.
Asturias, Isaac Albeniz (orchestral version)
To test if your tracks selection is good, load them all up and put them on shuffle. If anything sticks out, edit or get rid of it.

In Play

Grab a tablet and use a program or a folder that lets you see all your tracks at once. You'll also need a volume slider so you can fade out one track, switch, and fade in another track. With practice you'll be able to do it while talking.

Finally, because youtube if fickle and I like future-proofing, here's a version of this post with all the names of the tracks listed.