I have been doing ALOT of research lately, but based on what I know, I can tell you that you will need about 10 gallons per gekko. You can use chips, sand, newspaper, paper towels, and slate as a substrate, but be aware that chips and sand can cause impaction, which is even more prominent of a danger in younger gekko's. And then They need a hot side, and a cool side, so a heating lamp or a under heater will be good. They need to be fed once every day to every other day or sometimes every 3 days I have heard. It's also a good idea to dust the crickets and mealworms with calcium. They need freshwater every day, and need a "humid hide," which basically is a cave with a higher humidity than the surrounding area, and this can be a tubberware container with a hole in it for them to get into, and it has a moist substance on the bottom. And there should be a hiding spot for every gekko.
That's about it off the top of my head. And if anyone with more experience than me wants to correct something, go right ahead.