Now I'm just a basement hobbyist/woodshedder. I tune to whatever track I'm playing along with. Mainly standard, but the EVH trick of flattening the B string a little bit works (there are a number of "microtweaks" that work pretty well IFF you're playing a song that confines you to certain positions--& there's an overall "tweak" system--see below). I don't bother much anymore, but if the beating gets too annoying, I just trust my ear.
Check this out:
http://www.guyguitars.com/eng/handbook/Tuning/tuning.htmlBack when I played out, (depending on the singer & other instrumentalists), usually flat "standard".
With a keyboard player, I'd have one guitar standard, at least one flat--if more than one, they were in different keys (so the keyboard player didn't have to accommodate the limitations of a guitar tuned to standard pitch).
Usually played slide + fingers in "standard", played around with G a little bit.
I tried to avoid alternate tunings (mental block against learning nomenclature)--often revoicing chords &/or rearranging parts--but sometimes, there's no way around it; in that case, whatever the big shot did on the original. Where did the "shrug" emoticon go?