You can keep a pair in a 12"x12"x18" enclosure. They are fairly territorial and best kept in pairs.
They are very fast so your enclosure has to be escape-proof.
They are a hardy species provided you buy them as captive-bred. Wild caught ones will be loaded with parasites for sure, so resist the temptation to buy cheap WC ones.
Use flat, smooth-edged stones placed vertically, some stout branches and a water dish; the substrate does not matter much, you can use 1" of fine sand or garden earth once sterilized through the microwave oven.
A 40 watts basking lamp will be enough for such an enclosure. You can use any bulb with UVA, i.e. halogen bulbs. They don't particularly need UVBs and have to be fed 2-3 times weekly with appropriate sized live insects, properly gutloaded and dusted (see our forum on feeders).
A 2-3 months winter brumation with temps in the 60-70°F range is strongly advisable both for breeding them and for their health.
