When evaluating candle warmers, prioritize adjustable height and dimming functions, as these allow users to control the heat intensity and scent release rate. Ensure the heating element is a halogen bulb (typically GU10, 35W-50W), which provides the necessary thermal radiation to melt wax evenly. For the base, high-density marble, solid wood, or heat-resistant metal is preferred to ensure stability and prevent surface damage. Always verify that the internal wiring is heat-insulated to withstand prolonged operation.