I love chameleons but they can be fairly difficult to care fpr. Well, maybe specialized is a better word..
First thing first, I recommend getting a male. Females lay eggs whether or not they have been bred, and this can lead to many complications including death by egg binding.
Mesh or screen cages are important, or a custom cages with a lot of ventilation. They live high in trees in the wild so ventilation and air flow is important. No glass tanks. The enclosure should be high and you should have lots of foliage (preferably live) for them to climb, and vines. Keep the cage in a low traffic area to keep stress down, they can be very easily stressed. Substrate is usually not recommended to have, I use paper towle. It can be a bit harder to keep up humidity but chams can get easily impacted.
You need a UV light, tubes are the best. Use Reptisun 5.0 tubes, NOT compacts! They have been known to cause blindness and death in chams.
Temps. They do not need super high temps. About 90f in the basking spot and mid 70s in the coolest areas. Temps can drop into the 60s at night.
Water. This is one of the most important aspects of cham keeping. They won't drink from a dish. You need to have a dripper going for a few hours every day. You can buy drippers or make them yourself for super cheap. Chams drink a lot so this is key. You also need to mist a couple times a day. Many people recommend misting for 5 mins or so, this isn't always necessary but you do need to mist a pretty good amount. You want your humidity round 70% but not constant. Many people I know do not even measure their cham's humidity. If the urates are white then your cham is hydrated.
Variety of feeders is also important, I feed my cham lots of worms (silks, horns, butters, supers, etc) along with a staple of crickets.
Keep handling to a minimum as most chams don't tolerate it very well. Mine gets very pissy when you try to take him out so I normally leave him alone to prevent stress.
That is all I can think of right now. Go read as much about chams as you can before buying one as they are not for everybody. These are the absolute basics of keeping veiled chameleons. Hope it helps!