I find that I usually bring up everything to unity. Then do a quick balancing amongst all tracks. Then, I move to tweaking the drums, then guitars, then bass, and finally tweak the vocal last.
There have been a few times (RARE) that I start with the vocal and drums together because I find them to be the 2 loudest elements in the mix and the vocal track is really slammin'. More often than not, I'm trying to "repair" the vocal so I do what I can then try to convince the band that the vocal should be "audible" in the mix, as opposed to completely buried and covered in effects, because it's what 99% of their listeners will identify and latch onto upon first listen.
Hmmmm that gives me an idea for another thread as it's the situation I'm currently dealing with, with my most current project.....