Never offer Money.
They will feel like You/He are buying their Friendship.
If they drink, buy some nice wines for dinner, take them out for dinner, gift cards may be nice but again, may seem like buying them.
Have Him do nice things so it doesnt seem like buying them.
Hell, I had to do that with My Parents and My Wife (EX) was not with Me. Wow, like still living at home but free!
Tell Him, not to be a slob, pick up after him self and do his own laundry!
Keep out of the way if need be!