Help your kitty to get adjusted by placing the litter box in a place then picking him or her up and taking them to it. Show them where it is, and let them look around. Cats will inevitably look at everything and explore for a bit so they feel comfortable.
Show them their food bowls as well. Cats are anatomically built for more desert like conditions. Therefore believe it or not, they used to get their water supply from their food as well as from water. Wet cat food is far more healthy for their bodies. If you find this too expensive, then make a mix of wet/ dry food or simply wet their food with water and mix it up.
Establish boundaries with fluffy by keeping him or her in a particular room and letting them know that is where they stay, or allowing them to roam freely.
Brush and play with your kitty often to keep unwanted extra fur off the furniture and carpet. Especially if they have long hair. Play with them to facilitate growth of their brain, and a healthy mentality.
Teach them that playing rough is not acceptable behavior. This happens especially if they are kittens. If they start playing rough, especially with a child teach them that this behavior is unacceptable by taking their paws off of you calmly and pulling claws away if need be, then ignoring them. They will soon learn. Don’t allow children to prod them to play with hands, but give them a string or toy to have them catch if they are hyper. When they are more calm is the time for petting and hands on play.
Don’t forget to clean the litter box decently often or invest in a self cleaning litter box, because cats prefer to poo and pee in something clean! (That’s a cat for ya!)