Final stage of mastering involves 'programming'.... That's putting the songs in an order that flows naturally from one to the next... no songs with the same beat next to each other, or the same key to each other (if that can be helped), or essentially the same type sounds.

And then, it helps to listen to how each song ends, and then WHEN the next song starts. Most CD burning software allows you to put a variable gap between tracks, but will put a default 2 sec (or whatever it's set to) there if you don't alter it. Listen to at least the last third or so of a song (to get 'into' it) then listen to when the next song starts.

Does it seem too late, or rushed? There's a natural 'space' that the end of a song needs, a chance for you to digest what you heard, to relax from the beat etc., before the next one starts. But there is no hard and fast rule. Each CD is different, but you will often find yourself coming to the same conclusion after a couple of listens. the next song is often too early or late if you just use the default track gaps.

It's a small detail, but it adds a level of polish and listening pleasure on top of how good each individual track is. Software makes it SO easy to experiment with this, re-order your CD (and actually listen to it rather than guess whether each transition works), unless you are rushed beyond belief, it's worth the time it takes, IMO...

BTW, doing this can often make you more aware of whether a track is a HAIR too loud or quiet (it often depends on what tracks surround it). Adding or cutting a db or two at this point is usually fairly easy thing to do to the mastered file (with a limiter for gains) and adds a final level (!) of polish to the project...