Buy only heaters with Underwriter Laboratories safety listing
Check the safety features: does it shut off automatically if tipped over?
Do the grill, cover or sides ever become too hot to handle?
Is the grill designed to keep heating elements out of reach of children's fingers or toys?
Do look for a thermostat control that shuts down if the heater gets too hot and a tip-over switch that turns off the heater if it is knocked over. Decide which type of heater best suits your space needs.