Trimming your candle wicks is so important and it also happens to be one of the most common candle burning mistakes. The wick should be trimmed to just under 1/4 of an inch before every lighting, even before the first lighting. Some candles come pre-trimmed, some don't, so be sure to check. Also, be careful not to trim too short or the wick may not stay lit.
To trim the wick you can use scissors, a wick trimmer, or some people even use nail clippers. After trimming the wick down, make sure the surface of your candle is clean and free of wick trimmings and debris before lighting your candle.