I use three core symbols with each prayer vigil. They are Air, Fire, and Water.
Air is all the prayers that are said, also the spirit and the divination, so we know what is going on and how Spirit wants the vigil to be done. Air, the winds, also carry the prayers to the person being prayed for. There is also visualization, to see the person's energy field, to do cleanings and blessings. The Fire and Water represent the energy of fire and the reflections of water. Often in the water there are symbols and indications of the work, similar to scrying or reading a crystal ball. Each vigil has simple offerings made to it, to feed the prayers.