I wrote this a few years ago for the Home Recording forum; it may be of some help here:

Mixing is harder than it seems. Try this:

First of all, get away from the track for at least two days if you can. Avoid listening to anything you've done; listen to stuff you like by other people.

Ok, once you're ready to start mixing, try this method: Bring up just your main vocal track till it's at a comfortable loudness level. Now, slowly start bringing up the other tracks, one at a time. As you bring up each track, stay focused on the sound of the vocal track. If you bring up a track that seems to make the voice sound a little softer, shut the fader off for that track and go on to the next track, always listening to the vocal track as your reference, killing any track that makes the voice sound softer.

After you've gone thru all the tracks, you'll probably have 3 to 5 tracks shut off. Those are your problem tracks. You'll hafta eq, pan, compress, or reverb them, or leave them off altogether.

But listen closely to what you currently have going. Do you "REALLY" need "all" of those 5 missing tracks in the mix? Does the mix sound stronger without them? On the tracks you absolutely hafta have, put them where they don't cover the vocals, using any of the tools mentioned above. Then take about an hour break, get out of the studio, and come back later and listen to what you have. If you're satisfied, shut everything down, leaving all your settings in place.

Come back tomorrow and listen to it again. Tweak till you're happy, shut down, and repeat again the next day. The day you walk in and you're happy with what you did last night, is the day you have a finished mix.