I use a bag of store bought potting soil for house plants, into which I mix about the same amount of our homemade compost (mainly lawn clippings, garden waste, and some burnt over charcoal ash from the grill,).
I also add a couple of handfuls of bat guano to the mix.
While the plants are growing I, from time to time, dig gently about the surface and put in some compost right on top.
that's about it.
what it looks like.