It is not a good idea to burn candles with fragrance while cooking or eating.:

To prevent candles from boring a hole down the middle, burn candles for at least one hour for each inch in diameter. For example burn a 3 inch diameter candle at least 3 hours each time.   Burn long enough to achieve a melt pool that can be seen all the way around the glass.  

To achieve maximum burn time, and to alleviate the jar from getting too hot, do not burn for more than four hours at a time.  Extinguish, let cool, trim wicks, then re-light.

To extinguish candle and trim wick at the same time, cut tip of mushroom while candle is burning.   This will extinguish candle, without smoke, and wick is trimmed for next lighting, or dip the wick into the liquid wax, using a non-flammable instrument, then trim wick while wick is hot. These little known techniques eliminate smoking.  Always remove carbon deposits or other foreign materials from the liquid wax when possible.

Should your candle burn unevenly due to a draft, etc, consider this. Carefully push the wick towards the higher side. Repeat this practice a few times and the candle will repair itself.

Place the candle in an area free from drafts. The first time you light the candle, allow it to burn until the liquid wax covers the entire top of the candle. This breaking in process insures that it will perform better and more evenly throughout the life of the candle. This will insure a clean and efficient burning cycle for the life of the candle.

The wick is designed to produce a small black carbon cap at the top of the wick as it burns. This is normal as it helps radiate heat to the edge of the candle.

Never leave a burning candle unattended.  Keep wicks trimmed to 1/8-1/4 inch.   If you notice a large flame during burning, blow out the candle & trim the wick before re-lighting.   Place burning candle on heat resistant surface.   Never move a candle while hot or burning.   Blow out the candle if jar becomes excessively hot.   Keep out of drafts.   Keep out of reach of children.