Sanding the ball will let it grab more in the front, oiled part of the lane.  However, this generally means dissipated energy in this area and the ball will not hit the backend as hard.

I agree with the above post, the Nasty Nail is not designed to be a big hooking/heavy oil ball.  The best solution is to go with a more aggresive ball, if you want to stay with Hammer, something like a Sharp Blade.  If you want to stay with the ball you have, sanding it is a good idea, and should make it hook a bit more, just take it into the pro shop and tell him/her you want your ball dulled up.  This is all assuming you're playing the lanes correctly and not trying to bend the ball on a condition that will not allow that to work.  Good luck!