ask one of the players
'Oi what key is this in ?'

chances are it'll be D or G as thats the only keys most malodeons play in

try and recognise minor based tunes to major ones.

Just play the bass notes dont wory bout the whole chord

keep yor eyes on another guitarist.

Dont be afraid to ask and talk.

Most tune have 2 parts an A and B and the session may play the twicee each then again, and some times again, and again before changing the tune entirely, setting 2 or 3 tunes together

Some tunes have 3 parts

During some sets there maybe a change of key

now as for webfolk   PISS-OFF