Here are some general safety tips all candle makers should follow while working.

• Never use lead wicks.
• Do not heat wax directly over an open flame. Use a double-boiler, presto pot, or turkey roaster.
• Always use a thermometer when melting wax, taking care to not allow it to heat above @225.
• Excessive additives/oils (including scent) can be a hazard. Wax will only hold a set amount of scent - for one pound of wax, most use from .5 to 1.5 ounces of scent. Colors used in your candle are also like oils, and can affect the way it burns. A sign of too many additives is a candle that smokes even though the wick is properly trimmed. Always test each formula thoroughly.
• Only use fragrance/coloring specifically made for use in candles
• Only use containers specifically made for burning candles, capable of withstanding the extreme heat that will be produced.
• Take care in choosing the best wick(s) for each formula. Indications of a wick too-small are a candle that quickly 'drowns out', or a melt-pool that does not reach to the outer edges of the candle when burned properly. Wicks that are too large will produce a flame in excess of 1", and may develop melt pools deeper than 3/4", a sign that excessive heat may be present.

Read candle making troubleshooting tips from the Candle Cauldron