One book that really helped me here was Mike Senior's "Mixing Secrets".  I highly recommend it (along with Roey Izhaki's "Mixing Audio").
 
I used to load up compressors everywhere, start mixing etc.  He suggests getting a basic balance first (static fader), then look for the tracks that make you reach for the fader to bring them up or down as the track plays back.  These are the ones that might be helped with compression, etc.  If a track stays stable throughout the song, leave it alone.
 
I am obviously simplifying his thoughts greatly.
 
I listened back to some tracks I did in Sonar 6 recently, that were simple, static fader mixes with little or no compression or EQ, and they stood up quite well.  They could obviously be improved greatly, but didn't sound so far off, considering the amount of time, effort and processing that my current tracks receive.
 
Anyway, read Mike Senior's and Roey Izhaki's books, they have been invaluable to me.

I have shared the same experiences.  It seems like the more I messed with it.....the worse it got.  I recently attended Alan Parsons' MCTS Class and the major take-away that I had is to keep it simple.  When you take the time to get it right in the tracking stage, the mixing and production becomes much easier and you have to make very few "fixes" and don't require any more than a few basic processors.  To paraphrase what Alan taught us....... "take the time to get it right coming in".  I think that this is a valuable piece of advice.

On one of the recordings that we made during that class here's a summary of the processing that he used.  Added some 10K (actually....a lot) to the snare channel, had the bass player compress his signal coming in to the mix, and he used a couple of Fairchilds on the lead and backup vocal tracks.  That was it.  He did however spend some time making sure that what he was getting to the board was what he wanted to hear before any tracking was actually done. Coley Read (the Pro Tools guy in the control room) basically did tracking, a few overdubs (by punching in and out), a few clip "fade-in/fade-outs", and a couple of very minor touch ups.  He really didn't have to mess with things too much.  I really expected to see tons of things being done and processed in the DAW, but it was used pretty much as the digital recorder.  Admittedly, the studio musicians were awesome, the facility and equipment were second to none and that certainly adds a lot to the tracking process.  I think that "getting it right coming in" though was the biggest contributor to a great mix.

Anyone that gets a chance should attend one of these sessions.  I thought that it was a real eye-opener.

Keep Rockin'!

Dave 

Lots, and I mean like every soft synth/ sampler out there has presets which are already processed with compression, reverb, you name it. Adding additional processing to these can lead to gaseous explosions, so either remove the processing on the soft synths, or mix them to a separate bus and concentrate on the dry stuff to achieve a coherent blend. Or just turn it off and take a walk.