Why do ever question asked about mic's do I want to say "It Depends"? Depending on scheduling and the kind of/age group of the shows. I generally perfer that any kind of Heavy Makeup/
airbrush stage makeup happens first, I'll wipe a little
bit off on the cheek If i need to to get mic tape to stick, and then let them know then can reapply color or whatnot as they need to.
If they are doing Adams Family, (Fester) or Shrek, (shrek/Donkey) or other heavy makeup show I approach it 2 ways. Either they mic first, and I'll tape the head of the wig elements over, and uncover it when they are done, and/or I put them in "mic I'm willing to loose" and tell them to be careful, and contentious of it.
For a quick
turnaround time on my end, I'd prefer to always mic first then have light/standard
stage make up applied after. For a couple of reasons. It's better use of my time, with out the added steps of clearing off cheeks (though many times' I'll ask actors to go easy on which ever side there mic will be on and let them know they can finish it up during half-hour.) And the actors do have 30 minutes to finish makeup/dressing them selves before curtain where as I need to be finished with my preshow setup before half hour.
If Wigs are involved I like them MIc'd up first/ either over the ear or on the head before the bald cap/wigs are applied. Then I'll tape and secure/position the mic after.