Always trim your wicks to 1/4 inch,
unless told differently by manufacture,
ie. PartyLite's 3 wick and tealight wicks
should not be trimmed for optimal burning.
Why should your wicks be trimmed??
1) This will prevent the candle from getting too hot and the wax will melt too quickly. This will shorten the burn time of the candle and possibly crack the holder it is in.
2) Wicks are made of organic materials like cotton and wood. When these items burn they all create soot!! When you keep your wick trimmed you reduce the amount of soot produced keeping your holder from turning black.
Please burn your candles responsibly