Though we're wearing them downrange, there still isn't (as far as I know) any published wear guidance. I think we made it up.
EDIT: The convention was tan undershirt, tan web belt, tan boots, brown name strips, black or brown rank (depending on the color of your insignia). E's wore brown chevrons. American flag on left sleeve, squadron patch on right...oh, and lots of morale patches. (because show me in the reg where it says they aren't authorized on my two piece flight suit)