I am no expert that is for sure but I have learnt a few things.
Different candles of the same type/brand can burn at different temperatures. Even ones specifically for wax play can be too hot. Certain additives eg fragrances, oils and colours can make them hotter.
We always try new candles on our arm/hand first then less sensitive areas, shoulders and upper back. Moving to more sensitive areas as we are comfortable with the candle.
We start holding the candle really high and come closer as we are happy with the heat of the candle.
Make sure you are nice and warm when first starting out with wax play it makes it easier to absorb and enjoy the heat.
To rebuild your confidence I would start with a massage candle. You can melt some wax. Blow the flame out and let it cool slightly. Your master can pour some in his hand first then rub it on you. As you are more comfortable try dripping a little on a less sensitive area, I suggest shoulders. As you become comfortable with that maybe pour with massage candle. Then go back to the other candles. Finally I would say buying wax pots is a great idea. You can heat the wax to your preferred temp using a thermometer (until you get the hang of it). Take it away from the heat and use a spoon or whatever to drip. Pouring is also pretty awesome once you get comfortable with it all.
I am sure the more experienced subbies will have better suggestions but I hope this helps some.
Happy playing.
LG ?