Hang a towel or something over the top of every door in the house - kittens can be very easily killed or seriously injured by a door slamming on them (seen this in an animal shelter, people would bring in half dead kittens that they "found"
Make sure everyone
takes off their outdoor shoes in the house - same again seen kittens with broken legs from people standing on them
Put the litter tray inside a lidless cardboard box, or put newspaper under it, kitties will kick that stuff everywhere! Don't
"rub his nose in it" if he wees or poos somewhere - it encourages them to go there again!
Get him a scratch toy so he learns to scratch that and not furniture (but be prepared to have your furniture torn to shreds anyways!
Remember you no longer own your house or anything in it: everything is the cat's - your bed, your chair, your cushions, your blankets ...
Post pics of kitteh for us all to see!!!