As for doing what Glen said... I know enough from all of his advice on this site that I should always just do what he says...
While I appreciate the vote of confidence....GOOD LORD NO!

If you had seen my completely wrong initial answer I gave a couple of weeks ago about the operation of a mixer of the type I was sitting right in front of at the time, you'd know I make some boneheaded mistakes just like the next guy. Of course, I was sick as a dog at the time I gave that answer, but still...a boneheaded answer is a boneheaded answer.
If either you or Glen can confirm that I can safely lower my track faders in cubase LE I will get back to mixing my Stevie Nicks cover in relative peace and stupidity...
Yes you can. Think of it this way; if you couldn't mess with your track levels, you couldn't use volume level automation - level automation is basically dynamically changing track volume levels on the fly. So sure, adjust the track levels. In fact, I recommend setting the levels so that you're getting the "right" levels out of your master bus with the master faders set to unity.
I'd try to explain more about what I was saying about gain structure, but I don't want to bruise your brain any further here. Let me just leave you with a bookmark: head over to IRN at
www.independentrecording.net an click on the "Metering and Gain Structure" icon on the lower right to pull up an on-line interactive applet that's chock full of basic generic info on what the different meters along the line mean, how VU, DBFS, and RMS and other measurements actually mean and how relate to each other on a real and useful level, and some basic methods for setting levels all along your recording and mixing chain from mic to plug-in to get the most out of your gear and your signal. Play around with that applet at your leisure, take small bites and swallow between them, and you might just come out the end with no head injuries and an understanding of the common thread of levels around which all these widgets and doo-dads have actually been designed to work.
But for now, let me say this about track levels. When I sit down to start a mix, the initial set-up stages are usually a pretty quick 3-step process for me. This process is not the only way to skin the cat; others may take slightly different approaches, and that's fine. This is just what works for me. Maybe it'll help you out just a bit for starters, without having to go into a bunch of gain structure theory:
1.) I give the mix a faders-up listen. This means setting all track faders and master faders to unity gain (the 0 mark about 2/3 - 3/4 of the way up the fader. This tells me two things: first, how I want to initially adjust the track levels in step 2, and second, how good the tracking was and how much work I have ahead of me (the better a raw faders-up sounds, the better the tracking and the less work I have ahead in mixing.) I may or may not set initial panning at this point; usually I get the initial/basic panning scheme out of the way right then and there based upon what I hear.
2.) Based upon what I hear in the faders-up mix, I set initial volume levels for each track relative to one another, just getting them each roughly in the ball park for what I imagine in my head that I want the final mix to sound like. IMPORTANT here is that I never
raise any of the track faders. I just reduce each one by the amount necessary to get the relative volume roughly in line with where it belongs in the mix with the other tracks.
The faders virtually *never* (well, maybe one in 20,000 times only) go above unity gain. At least one track - sometimes a couple - usually stays there at unity; especially if they are quieter-recorded tracks that need to be loud in the mix. Those are the ones with the highest gain setting, at unity. Others might be 2-3dB down, still others may be dropped more than that; it all depends upon how the tracks were recorded and how the mix plays out.
3.) Once I have those rough starting mix levels set up, I switch automation on for all tracks, setting the initial flat line level for each track somewhere around 3 or 4dB down from the top (maximum) level. This gets me ready to individually start actual track mixing for the final mix, using automation heavily (see the current thread in this forum on texture and automation) to do my mixing. The extra 3 or 4dB of headroom I give myself allows me to move the fader/volume level for that track up by up to that much at any point, should the overall track level be a bit low and I need some extra oomph here or there.
Then I start the track detailing in earnest. The EQing, compression, automations, etc.; usually submixing the rhythm section (bass & percussion) first, then the accompaniments, the finally the leads and main vocals, in that order (usually, but there are always exceptions.) If I need to make fine tuning adjustments to the individual fader and automation levels at this point, I do. But I almost never send a fader or automation level above unity gain. The only real exception to that is if the tracking is soooo poor and uneven, and one track is so anemic and low-level that it needs the above-unity boost just to be heard. But even in that case, I'll try to get a re-track first if possible.
Usually for me, assuming that I have fairly decently gain staged recordings with behaved recording levels, the final mix winds up coming right out in the sweet spot fairly naturally, without having to touch the master faders, just leaving them at unity. There are exceptions, sometimes, but it far more often than not just works out.
HTH,
G.