It is tedious, but you check for shorts using an ohmmeter ($4 is the cheapest I've seen them on sale). Remove the fuse on the circuit you are testing. A hot circuit will burn out the meter. Check for continuity. If you have it, you also have a short. The meter will read infinite (or very high) resistance in a normal circuit. If it reads 0 or very low ohms, you have a short.
Isolating the short is the tedious part. Unplug all appliances from the circuit. If you still have the short, start disconnecting switches, outlets and fixtures until the continuity is gone. Start at one end of the circuit and work your way to the other end. Light bulbs are high resistance, but could be shorted out and not noticed.