Generally, it helps abstracting the problem away into the real constraints, in this case, the outcomes space, (i.e. 4 possibilities, that can be compressed into 2 bits of information bit 1 = 'same or different', bit 2 = 'head or tails', but in this case 'head or tails' is irrelevant), and then reasoning how each person communicates their bit of information to span the entire outcome space.