Tone, take a deep breath, get a cup of coffee or smoke a j, or do what ever it is you need to relax and get yourself into the state of open mindedness to accept all of the REALLY FUCKING GOOD ADVICE EVERYONE HAS GIVEN YOU UP TO THIS POINT.
Every one from Greg, Ray, Rami, Glen and John have all told you the same thing....but you seem to want to skip all those steps and go straight to a polished, eardrum exploding commercial mix.
That is just not going to happen.
First and foremost, nothing great can ever happen without a strong foundation. That means no matter what you do on the master bus, it will not matter if mix isn't balanced, with ample space for each instrument. A well balanced mix is not possible if each part wasn't tracked well. Sorry, but there is just no other way to achieve good, much less great, results if there are issues with the initial raw tracks. There is no way to get from point A(pre-production) to point B(a "commercial" sounding, radio-ready stereo track), without taking the time to do each phase properly.
I am by no means an expert.....just starting out myself, but if you listen and absorb what these very knowledgable people are telling you(repeatedly), you can achieve some very nice results.
Start with pre-production, sit down and flesh out what exactly it is you are trying to accomplish and convey with that certain piece.
Once you have a good working idea of what you want sound like, convey, and project to your target audience, then you can start tracking. Next, you need to make sure your source sounds pretty much just the way you want it to on the recording. How does your guitar sound? Is it in tune? Do the strings sound flat and lifeless? How is your tone? Tuning and intonation is crucial, with every instrument...even drums. How about room acoustics? If your room acoustics suck, so will the tracks you record. Whats the BPM on the song you are going to record? Can you stay in the pocket with your click track/metronome? If not....stop right here. Practice, practice, practice until you can nail the performance.
Tracking. If you have done your homework up to this point, then this is really just a matter of taking the time to do the tedious tasks of mic placement, and gain staging....these things take some serious time(at least for me) to get right. It just simply is not a case of pointing a mic at a source and hitting record. Each piece of equipment in your signal chain is going to have a sweet spot, that is the place where the signal will sound the best, noise floor, headroom, and the like are very important aspects to tracking. Gain staging issues has killed many of my "great" takes. There's a bit of art in finding the proper balance to accurately record your source. I use external preamps on most of my recordings, nothing fancy, but I like to try different "flavors" of musicality. I set my input levels so they are as close to staying in the sweet spot as I can possibly manage. Once that is achieved, I move onto setting the input on my DAW. I like to track with my source running about -12 dbs RMS, with peaks about -6 dbs. For me, it helps everything "sit" together better in the mix when I start trying to bring all the tracks together into a cohesive piece. If I record my sources at differnt levels, things just sound wrong when played back together. They dont relate well with each other and no amount of fader automation seems to help. They just do not work well with each other.
Now, if you are like me, you have an hour or two into the tracking phase and have not even pushed record yet.
Next comes the actual performance of the take. Don't cheat yourself or your final product by accepting a half-assed take. If it's not up to snuff, keep it, but record it again, and again, and again and again and......you get the point, until it is a "great" take. Sometimes you get a take that is fan-fucking-tastic except for.....(insert any number of reasons your not completely happy with a certain part) Go back and revisit those 3 - 20 takes that you have kept, is there a take where you botch the whole thing except for one little part that you nailed? Try comping the tracks, taking the best part of each take and making one glorious hit-record making take. If you have performed well, and stayed "in the pocket" with your click track/metronome, this is actually pretty easy....BUT TIME CONSUMING. Editting sucks in my opinion, but a necessary evil nonetheless. But I digress and am getting ahead of myself.
Rinse, lather, repeat until you have all the tracks recorded, synced up to your metronome. On playback you should be 93.43% satisfied with the way the songs sounds. If not, chances are you will never get it "fixed" without retracking.
I am giving you the condensed version here, I don't have the time or energy to type out every aspect of my recording process so I am assuming that all this is pretty straight forward and understandable up to this point.
Now that tracking is done, it's time to start mixing....my favorite part.
This is pretty subjective and I wont sit here and try to tell you what you need to do get a good mix. There are some guidelines and road signs that can direct you on the right path, but not much is really set in stone. Trust your ears, assuming they are trustworthy! If it doesn't sound right.....it's not, and EVERYONE, from average clueless listener, to the most experienced engineer will be able to hear it too. The difference being, average clueless listener will not know why it sounds bad, they will just choose to not listen to it again. An experienced eng will tell you instantly what you fucked up.
Once you have achieved a well balanced sweet sounding mix, and it truly is not that easy to do, then AND ONLY THEN, should you start THINKING about mastering.
Mastering. If you are having trouble balancing out your mixes.....you have no right to assume you can "master" that mix. Mastering is a science all on it's own. It is far removed from the mixing process and is usually done with a completely different approach and goal in mind.
Check out Massive Master's website, I am sure there are others too, but that's the one I am familiar with. Listen to the before and after clips. It is eye opening.
Mastering is so much more than, "make this fucker loud!" That is what breathes the life into the mix, the icing on the cake so to speak. It adds sheen, sparkle, and life to your already pretty freaking good mix. If it was as easy as slapping a limiter on that bitch and call it good. We would all be Rubin/Massenburg/Johns, or who ever it is you look up to in the field.
Your best bet is to humbly accept the "kernels" of knowledge that are regularily doled out on the forum from the very talented cats that take time outta there busy schedules to answer the same 16 stupid newb questions...over and over and over again. Accept them and study them until the light comes on and it starts making sense to you.
Like I said, I am just starting out in this amazing yet frustrating craft, so don't think I am trying to preach to you as though I know what's going on.....I lurked on the forum for years before I ever started trying to actually record, much less hand out advice.
Good luck and stay with it!