Upon first burn...
Burn your candle for at least 2-3 hours (8oz & 16oz), & 1 hour (5oz). Allowing the melted wax throughout all the edges of the jar. This will ensure a nice even melt each time you burn your candle.
Keep the wick trimmed to 1/4 inch each time you burn, and make sure any of the wick cuttings are removed from the jar.
Never burn a candle longer that : 3 hours (8oz & 16oz) & 2 hours (5oz).