Start him out in one quiet room with his litter box, scratching post, food, and water. Don't give him access to the whole house right away. Make sure he has somewhere to hide if he needs to and don't pull him out or bother him. Some are very shy and fearful to start and some are very bold, it just depends on their personality and doesn't mean there's anything wrong. Let him come out of his shell at his own pace.

If you aren't starting him out in your bedroom then leave some stuff that smells like you in his "safe zone" such as unwashed clothing or bedding so he starts associating your smell with comfort and safety.

When he starts showing interest in the door and doesn't seem very scared of his environment it's time to let him explore the rest of the house - try doing this at night when it's quiet and everybody is asleep so he can get to know his new habitat on his own terms without feeling too overstimulated.

It's normal for them not to eat very much at first and isn't something to stress about. Don't keep the food and water bowl next to each other, put them in different parts of the room. Don't move them or the litter box out of his "safe zone" until he's fully adapted to the rest of the house, you don't want an accident because he was too nervous to get across the house to access his litterbox.

That's about all I can think of off the top of my head, good luck.