Having played rhythm guitar on lots of Balkan music, and on lots of Zwiefachers too, I am fairly adept at this sort of thing.

it is pretty easy, if you remember that odd meters are all compound time which are a combination of "slow" (1-2-3)and "quick" (1-2)--

the Macedonian/Bulgarian Lesnoto, in 7/8, is counted as Slow...quick-quick, Slow...Quick Quick (1-2-3 1-2 1-2)--Strumwise, it's down-up-down down-up down-up--

You have to keep yourself honest by playing all of the beats, if you play what you think it sounds like, you will slip back into an even pulse without realizing it--

Balkan tunes tend to be a bit intimidating sounding, owning to the bent scales and pecuilar wailing sounds, so the uninitiated generally don't try to join in, but Zweifachers have that simple, happy sound to them, and you can have great fun with someone uninitiated who tries to sit in--