I got a logic probe a while back but never got around to testing it. That was a mistake as it’s a brilliant tool for debugging your circuit. Until now I have used my trusty multimeter to check for signals when my circuit is faulty. But that’s a pain to have one eye on the multimeter display and one on the test point. With the logic probe it’s much easier, one sound (and LED) for a high signal, another one for low and a third for a puls train. If there is no sound the connection is either faulty, not connected or at high impedance.
So my tip is really to get yourself a logic probe, it’s worth every cent!