I'm sure the soil your planning on growing on will be pretty void of nutrients. What does the natural vegetation look like around your area? It is probably like the soil around here, where it stays hot and dry. I would work as much potting soil/compost into the ground as you could. Maybe dig a big hole, replace with good soil, and haul the rest off. Though, you could just plant the seeds like they are and hope for the best, but you will get what energy you put into the plant/preparation at harvest time... Can you grab a big hand full of dirt from where you want to grow when it is pretty dry? Or is it pretty hard?

Watering: I would water maybe twice a week if it really hot/dry. They like to dry out a little bit, will make the roots grow bigger in search of water. You'll be able to tell when it needs a drink of water. Also if there are a lot of people around your area, and you have this plant that is really green and lush and everything else is dry and brown, it can really stand out.. fyi