When candles are molded into shapes, it is called sympathetic magic.

To assist in finding a familiar, burn a candle in the shape of the animal you desire

Fertility spells can be cast with a phallus-shaped or womb-shaped candle. Healing uses human-shaped candles or skull candles. White ones are for healing, black ones for reversing spells and warding off negativity. Different animal-shaped candles can be used for a specific purpose. Some examples are: dog – loyalty, cat – cleanliness, wolf – wisdom, bear – motherhood, rabbit – fertility.

Another type of candle magic uses pins. Stick a pin in as close to the top as you can without breaking the wax. As you insert it, say:
“When this candle burns to the pin,
The process of (name the desire) will begin.”
Insert a secont pin close to the first and say:
“When this candles burns to this pin
The process of (name the desire) will come to a successful completion and end.”
-This idea came from Silver RavenWolf

You can use birthday candles or very small candles for a spell that needs to be done quickly. You can also put drops of colored oil or food coloring into small tealite candles which also burn quickly.