Setting lights is a lovely service that many magical practitioners offer to the community. Sometimes setting lights is referred to as a candle altar service. Generally speaking, a client will tell a practitioner about their current situation, and the practitioner will decide what color candle and what herbs and oils would be best used to dress that candle in order to have the desired effect on the client's situation.
Dressing a candle is when magically-potent essential oil blends and traditional herbs that resonate with an specific spiritual goal are rubbed onto or worked into a candle, to impregnate the candle with the desired energies.
A small paper that has the name and goal of the client may also be prepared and will sit under the candle while it burns in order to help personalize and direct the energy even further. Such a paper is called a name paper or a petition paper. Petition papers usually include some form of a formal statement of the desired goal, and the name of the person the candle is meant to aid. Sometimes the name and petition statement will be written a certain amount of times for a stronger effect. In hoodoo 3, 7, 9, and 13 are common numbers used in work - but they are not a hard-and-fast rule. The name will sometimes be written in such a way as to cross the petition statement, which is a way of symbolically claiming power over the situation stated in the petition. If the candle is for money, dollar signs may be drawn upon it in the corners; if it's for love, hearts may be added. This just further solidifies the nature of the energy being summoned into manifestation by the candle. This petition paper will also usually be dressed with dabs of the same oil blend that has been used upon the candle. In some cases some of the same herbs which have been sprinkled onto the candle will be folded into the petition paper to make sure the request is well surrounded by the energies of the oils and herbs.
Having lights set is a very traditional way to have spiritual work done on one's behalf.