Always burn your candle until the whole surface becomes liquid. This step may take a long time, especially during the first burning. When the wax is liquid, do not burn it more than one hour. The top layer of liquid wax should never exceed one centimeter. Never burn your candle more than the maximal burning time indicated on the instruction in the candle, and never burn it totally. Systematically one centimeter at the bottom.
For more safety rules, please check our page The art of burning.