Soy wax remembers the burn radius of its last burn. I know that sounds weird, but just take my word for it. I suggest burning your candle for at least one hour (no more than 4 hours) to allow your pool of wax to reach the edge of your container.
Before you light your candle, make sure the wick is trimmed down to about 1/4".
Do not allow children (human or furry) or other people who shouldn't be around an open flame near your candle.
Keep your candle away from flammable objects, and do not allow any debris to collect in your candle.
Never leave a burning candle unattended.