Here's another trick to lower a mix without losing the balance; Insert the TRIM plugin in the last insert slot on all AUDIO and INSTRUMENT tracks and set to -8(suggested starting point). Its easier if you make the TRIM plugin default to a user setting first. Assuming AUX tracks are fed by Post-Fader sends, this will lower the entire mix but retain the balance.
As for red on a single track, solo it and listen for clipping. Sometimes its as simple as lowering the output(or input) of a plugin. Some plugins sound fine and some don't, so critical listening is important. Sometimes, using a different plugin can help(I was a bit shocked to hear the stock digirack compressor, compared to some other comps).
My session templates have the TRIM plugin built in on every AUDIO/INSTRUMENT track from the start, but they are all in bypass until mixing time(nobody worries much during tracking, assuming proper input levels)
