See https://duet3d.com/wiki/Connecting_a_bed_heater#Mains_voltage_AC_bed_heater for some minimum suggested safety precautions.
As DjDemonD says, with any sort of stick-on heater you need to make sure that the weight of the heater does not cause it to detach from the bed plate. On my printer, again the under-bed insulation helps to support the heater weight and press it against the bed plate.