Believe it or not you can extend the life of your candle by the way you burn it!!
In order to achieve a nice even burn on your candle you need to follow these simple steps, if your candle is 1" in diameter you need to burn it for at least one hour, this will create an even pool of wax around the wick.
if you burn it for any less time you will get a small pool around the wick and on re-lighting it will lead to tunneling. Tunneling is when your candle burns straight down the middle and you are left with a candle shelf. Like this ......
example photo on the way
So if you have a candle 2" in diameter burn for two hours, 3" three hours etc..
Don't burn the candle in a drafty spot as it will give an uneven burn
Finally always trim the wick before you re-light the candle, you want a nice gentle flame, enjoy!