Apple Final Cut Pro 7 - Manual (Page 1005)

Use the natural beginnings and endings of music clips for your edits
Instead of fading a piece of music in and out of a sequence at random points, try matching
specific parts of the music with parts of the video clips in the sequence for a dramatic
impact. Then, at the points where you need to start and end this music in your sequence,
edit in the beginning and the ending from that track, lining them up to match the rhythm
and melody of the part of the track that you’re using.
Using a music track’s natural beginning and end sounds much better than just cutting
into the middle of it, and you can usually create a series of edits using different pieces of
the same musical track to make it work.
Use subframe syncing to keep music on the beat
Since music has a consistent rhythm, inconsistencies in the rhythm caused by edits to a
music track can be painfully obvious. Since one-frame increments are rarely detailed
enough to ensure perfect sync of rhythm in a track, use subframe syncing for each segment
that you edit to make sure the edit points between two clips from the same song are in
rhythm.
Checkerboard the audio segments you’re using to create better cross fading
Instead of using cross fades to transition between two edited clips from the same music
track, edit them together across multiple tracks in your sequence:
Instead of
placing audio
tracks like
this...
...do this.
Now you can use the audio level overlay to create cross fades that are as long as you
need, creating the shape that will make the transition from one clip to the next least
noticeable.
1005 Chapter 61 Tips for Better Audio