I started by buying a mixed size pack from ABDragons. There were about 600 of them with no adults. It took several months before I saw a new generation appear. If you want this to happen more quickly (but at increased cost) I'd order some adults. Maybe a dozen or two with about a 3 or 4 to 1 female to male ratio. Other than that, they are pretty straightforward to care for. Give them housing and feed them and they go about their business. I like to include leftover salads from my dragon and any kitchen scraps that my dragon can eat. Roaches love squash and the occasional orange slices. Fresh veges help keep them
hydrated too.
If you find that the frass starts to build up too much on the bottom, you could introduce a cleaner crew of bugs. I just added a small order of superworms to the mix and they have worked pretty well as a cleaner crew.