When I'm mixing, I'll always strap a compressor across the 2-bus, but it usually isn't set for much gain reduction, at most usually 2-3 db, with a low ratio(oftentimes 1.5:1 or 2:1). I'll play around with the release and attack to get a fair representation going on. Although I prefer to do this with outboard gear, if I'm doing this at home or at another small ITB studio, I'll go with a McDSP Analog Channel plugin(if I'm in Pro Tools) or the Waves Rennaisance Compressor(not great, but it does the job). I learned mixing this way, and have always done it this way. It provides a sort of "glue" to the mix, helping it tighten up. One thing you have to watch out for, though, is unseen clipping, so every now and then, bypass the comp and check if you're clipping the master channel, and if you are, adjust accordingly. It can get nasty if you don't. If I'm working ITB, I won't put an EQ on the 2-bus, but if I have some nice outboard EQ's(it depends entirely on whether or not I'm familiar with them), I'll add a really small amount of high end, or, if the EQ's are coloured enough and the mix doesn't need that little bit of sparkle, I'll just put the EQ on the 2-bus and leave all the settings at 0, just to impart the colour. As with everything in recording, though, there are no rules, and you should do whatever works for you. I think Andy used to mix into his Finalizer so his mixes wouldn't entirely be wrecked by the mastering limiting later on. It makes sense to me if I was in his circumstance, but I usually end up having my stuff sent to a ME that I trust, or who historically has done solid work, so I'm sure that my kick and snare won't get entirely messed up in the process.