Keep it moist, give it a spray every few hours.

Is it going to come planted in soil? If so it will be much easier for you clones are quite hard to get going at first. Dont give it nutrients until it's a decent size and put half a big 'soda' bottle over it for humidity if it's not planted.

In a closet I wouldn't recommend anything over 600w, use a small fan moving across the plant to give it good strong stems. A carbon filter is good for getting rid of smells though they can be expensive.

I've been using coco soil it's trouble-free.