IMHO it would be prudent to make at least basic preps for an EMP event, most such preps would be useful for other problems as well.
To keep stocks of food, water, fuel, tools, clothing etc. is clearly prudent since any emergency, whether EMP related or not, is likely to disrupt normal supplies.

As regards preps specific to EMP, mine include spare radios, battery TV set,PV charge controllers,led lamps, and 12 volt flourescent lamps. All are stored in metal containers in a metal cupboard.
Since a nuclear detonation is the most likely source of an EMP event I also keep Geiger counters, which would also be useful in the event of a civilian nuclear accident.

EMP damages electronic equipment by inducing damaging voltages and currents in conductors.
Therefore anything connected to long wires or other conductors is more vulnerable. A landline telephone still in the suppliers carton is much less vulnerable than one connected to a phone line for example.
A P.V. charge controller connected by long wires to an array is far more vulnerable than one sitting on the shelf.