Make sure to trim your wick before each lighting or once your candle has cooled to room temperature; never attempt to trim a burning candle. Place the trimmer's long handle against the inside of the jar's rim for guidance and bring the curved scissor blades to the wick, about 1/4" from the base and parallel with the wax. Trim your wick and discard the snipped portion in the trash. As a safety precaution, never leave wick trimmings (matches or other debris, for that matter) in your candle jar!
