It is good to throw hooks with the elbows close to the body.
A whole bunch of body punching is setting up the punch, and getting your feet in position so you can land it effectively. Another thing, in my mind, is punch placement; you can do as much damage with one well placed shot as with dozens of here and there attempts. I would suggest always practicing body-punching (or any punching, really) off of a defensive move, like a slip, for example