If you are placing music in your missions, try to do it the same way films do. Pick a song that fits the situation, something that sets the mood. If you are showing a sad cutscene, you probably don't want Bobbie McFerrin's "Don't Worry, Be Happy" playing. And if you are playing the music during the mission where the player is a fighter pilot in the middle of attacking a heavily-defended base, then Pachelbel's "Canon in D Major" is probably a poor choice.
An example:
Action scene, you are Vulcan gunner defending against several nasty bombers....AC/DC - "Big Guns"
Music choice is loud, sounds well even over roaring vulcan. Good tempo and beat, just the right BPM I think. Song title also matches the situation, 'Big Guns'. Popular band, very few would not like this kind of song.