Cacti require a well-draining, rich soil in which to grow. Many garden centers and florists do carry premixed soils especially for cacti. These have the advantage of being ready to use. To this mixture you can add some horticultural grade charcoal, grit, or fine gravel. If your soil is on the acidic side, the addition of some lime is recommended.
Most cacti require full sun.
Seedlings and young plants will tolerate some shade, but will not develop properly. If artificial light is used to supplement natural light, check frequently for the proper candle power. Cacti need water, but have evolved to use it carefully. Watering should be done when the pot is completely dry. When watering, water thoroughly until the excess comes from the bottom of the pot.