In the studio it's always my tuner and mixing people live it's always the artist(s) call.
For our Monday night session we always tune ourselves to our own tuners after leaving instruments to acclimatise. There's only one other guitar player and not only is he a (not THE) southpaw, but he has his own open tuning and the two work together - this guy makes his guitar SING!!!! Perhaps it's the plethora of different instruments - average Monday, not busy -
2 guitars, one mandolin, one banjo, one Irish bazouki, one concertina, one uke, 3 harmoniums, one piano accordian, Northumbrian pipes, penny whistles, recorder, 2 violins, two bodrans (pronounced Bohran) various voxes AND a hammered dulcimer. All acoustic!
If everyone plays together it's all you can do to hear your own instrument and vox, but thankfully this doesn't happen often and theirs plenty of opportunity for small groups to spring up here and there and most people are considerate.
Wouldn't a tuning fork go out with air pressure/temperature/bangs and dings more than an electronic tuner? Don't know, I'm asking.
The best tuning is to be had with a Strobe tuner
or an oscilloscope, but these are expensive.
I would love to know if anyone has any different techniques but I almost exclusively use the 12th fret harmonics through the pick-up of my electro-acoustic.
And, it's important with any stringed instrument to tune it from flat to tune, never from sharp to tune - it avoids the slack taking the strings flat (ter) as the tension only builds to in tune.
But aint that what makes this such a wonderful world? that most people do things differently giving the learner the chance to pick what works best for them.
Except in my studio - less time wastage, less arguments!!! 
