Candles
Candles are an important everyday tool of the Craft. They come in every colour, can be scented or not and represent each of the four elements all by themselves. Some of the most simple spells out there involve nothing but a candle and your will. A white or black candle can be substituted for any other colour, as white and black aren't colours themselves, but the combination of all colours or the lack of them (white and black respectively). Its' a good idea to keep a wide array of colours and types of candles on hand. Usually you can pick them up at local dollar stores for a quarter a peice, a bit more for the larger pillar candles.
A candles form is solid like the earth; the dripping wax like water running, the smoke as air's breath and its' fire the fire of life. A candle is a powerful magical tool if you keep that in mind. They can also provide simply light and scent to other magical workings, and set the proper tone for an event. Personally, I think candles should only be lit using a match, but others who are a little more techno-Pagan than I am will argue otherwise. A candle should never be blown out, as it insults the spirit of fire (and may splutter wax wall over the place). Instead, pinch out the flame at the base with dampened fingers, or snuff it with a candle snuffer.
Finally, where to keep a candle burning? The bathtub is the single best place in your home to leave a candle burning over night or for long periods of time if you have to go out. If the candle falls over, it wont catch anything on fire, and the bottom of a tub is usually pretty damp so it's double safe besides being made out of porcelain. A candle spell is best left to just burn until the candle is gone, and please, only one spell per candle!