One minor point: if you've got tonal elements from both tracks playing at once during the crossfade, make sure they're not going to clash. This guy picked one track in A minor and one in Eb minor, and they're a tritone apart, so it sounds a bit messy during the crossfade. Pitching the second track down half a step would make it a perfect fourth, which sounds nicer, but if you don't want to bother with stuff like that, try crossfading them when one of the tracks only has percussion going.
