| Cacti of just about all persuasions like a very well drained soil. They also don't like much organic matter in the soil. You can actually buy premixed soils from any good nursery. If you want to make your own, there are many many different recipes. All based on good drainage. This year I myself have used a mix of 2/3 decomposed granite that has been washed to remove the very fine clayish particles, and 1/3 normal dirt from under the lawn. | 
