I have experimented on what I have here. So far the simplest for me is use store bought cactus soil and add lots of pumice. I used to go for perlite, but I find pumice better, perlite is so light. Then I also found adding akadama and kanuma good, just enough moisture retention and yet drains well, good for those non desert type succulents. Then I also found chicken grit, the one that is insoluble crushed granite as a good top layer on the soil, some low growing succulents leaves tend to touch the wet soil and this top layer is a good layer to protect it. Really thankful for the folks at the Sempervivum thread here in ATP that is where I found out about using chicken grit.
I also like to mix in those crushed lava rocks if I have them..lots of air holes there, good for the roots.
