The first burn is very important in determining the candle's lifespan. Allow the wax to melt across the entire surface and pool at the edges when lit for the first time. It will prevent tunnelling (the small crater at the centre of the wax) and make your candle last longer.

Every 3 hours of burn time, trim the wick. Maintain it at 5mm at all times.

When trimming, first, put out the candle and let it cool down to room temperature. Check for debris and make sure to remove it before lighting it up again. By doing so, your candle will burn cleanly and evenly. 

Additionally, it’s best to avoid burning candles for more than three hours at a time. The candle should be allowed to cool for two hours after burning for three hours.

It's risky to blow out a candle because soot can form, and hot wax can splatter. To properly extinguish a candle, you should do the following: 

Use a snuffer.

Dip the wick into the melted wax using a wick dipper. 

Do not use water, as it can break the glass of the candle jar.