To take care of a cactus, you should:
Grow cactus plants in well-draining soil.
Water only when the potting medium is completely dry.
Place in a bright sunny location.
Give 6+ hours of sunlight per day.
Avoid overwatering and high humidity.
Use a fast-draining soil mix designed specifically formulated for cacti.
During the spring and summer, when your cactus is actively growing and blooming, give it a hearty drink every ten days, allowing the water to drain thoroughly.