Be sure to trim the wick to 1/4" before each lighting. During the first burn, allow the candle to burn for 3-4 hours to achieve a full melt pool (liquid wax from edge to edge). This aids in preventing tunneling with future burns. If a tiny bit of wax remains on the sides, it will eventually melt the further the candle burns down as candles burn hotter as the wicks get lower down the jar. Avoid burning the candle for longer than 4 hour increments. Never leave unattended and keep away from flammable materials as well as children and pets.
Remember to ALWAYS TRIM YOUR WICKS PRIOR TO EACH LIGHTING! Trimming your wicks ensures that you're taking the precautionary steps to burning a safe candle.