Using both the hashtag and raw search on the words #fiddle , #mandolin, and #banjo and following folks who actually have posts talking about #music. No "mandolin slicers" or people just fiddling around.

Less interested in bluegrass and classical violin, more interested in "#OldTimeMusic" dance tunes, blues, jazz and #folksongs ... while trying to make the transition from playing such things on the guitar or mandolin to the fiddle, at a rather advanced age for such adventures.