Always burn a candle for at least an hour to allow the candle wax to melt properly and provide sufficient time for the scent to evaporate. Observe where the candles are placed. If a window is frequently opened or the room is air-conditioned, these factors can affect the strength of a scent. Before lighting the candle, trim the wick. The wick length will impact the burning quality of the candle. For example, if the wick is too long and overburnt, when lit, it will create heavy smoke and block off proper heat transmission to the surface of the wax.