Trim your wick to the ideal length—¼ inch—and make sure none of the trimmings remain in the wax: "Debris in the candle causes the flame to flicker too high, which leads to soot and blackening of the glass
The first burn is very important—the candle wax must pool to the edge on the initial burn. We always like to remind people that wax has memory, meaning that if your candle doesn't burn to the edges, it will begin to tunnel and won't burn evenly the next time.
If the tunneling isn't very bad, lay the candle on its side and use your lighter to melt the wax away from the wick and pour it into the trash. Relight your candle and make sure that you allow the wax pool to reach the edge before blowing it out. This will be messy as the wax will turn black when melting it.
Cut out the wax that is above level of the wick with a butter knife.
Remove the wax after its melted with a cotton ball or paper towel. After removing enough melted wax so that the wick is above the melt pool the candle should begin to burn properly.