I don't have any suggestions but I will mention that I was able to improve my mixing skills for free by logging onto www.metapop.com
and competing in remix competitions.
I did 18 remixes going back 25 months, more and recently I did another one to see if I'd absorbed anything.
Most of the remixes gave me an excuse to try a new technique. I taught myself some fun tricks trying clip-stretching, pitch shifting, extreme EQ (turned a kick drum into a shaker for one), parallel processing, reverse clips and other things including various combinations of all of the above. I also worked on adding/changing beats.
The recent remix I went in with no set learning path. I listened to the song, stripped it down to the vocals and listened to get an idea of how an arrangement would serve the song and then I went back to a playback of all the provided tracks and started deleting tracks that I felt were just there because somebody wanted to play them. I suppose that could be more of a "producer" than a mixer but those lines have become blurred.
After I tossed out enough tracks to get some space (including a horrible sounding "snare" abomination, I added a drum track and then used automation to keep the percussion under control a bit.
I only spent about 3 hours but my take away was "listen to the arrangement." That was a lesson I hadn't really learned on any of the other remixes.
I've never won, by the way. I doubt I'll win this one but that's fine. The lessons are valuable and might save tuition if one already has a handle on them.
Here is a link to my page, I recommend you surf around a bit and listen to what others are doing as well. The second (There Go Elephants) and third (That Itch) posting are bits I tossed up from other times and not really examples of mixing at all.
The first one is a recent remix and then Running Back is the last remix I did before that.
It may not be a good path for you and I certainly don't expect you to listen to any of my efforts, just sharing something that turned out well for me. I've got a better handle on mixing than I did previously.
I won't claim to know much about mastering, I do understand there that a consistent sound that works well on all platforms is the essence. I don't think my ears are that good yet, and I KNOW my room and speakers are not.
Good luck!!! I'll check back in to see what this thread stirs up, great topic! Cheers, Kuru