The first time you burn your candle, have it lit for at least 3 hours, or until the melt pool hits the inside of the mason jar glass. Every time you light the candle after, burn until the melt pool has re-established itself to the edge. This will prevent tunneling.
.
Trim your wick! If you are experiencing problems with smoking or your wick staying lit, it usually means your wick needs a trim. Wicks should be kept at 1/4" at all times. Your wick should be trimmed every 4 hours of burn time. This helps keep the flame the appropriate size for safety, and the longest possible burn time.
.
Keep your candle out of direct exposure to sunlight and light rays for prolonged exposure of time. For example, If left on a windowsill for a long time with daily sunlight eposure, you will start to notice the candle wax turning to a shade of yellow, This is an effect of the naturalness of our wax.