A Couple Of Thoughts…..

[dodgeman]

Skunks usually come around a particular yard for a food source. As Jay J’s link points out, they like grubs. Putting down a strong insecticide such as GrubX will help. Skunks can do much more damage than just digging a few holes. Thye can rut up your lawn to the point that you would swear that someone took a rototiller to wreck your lawn.
As to killing them, I can speak from personal experience that it doesn’t make much difference if you shoot them in the head, gut shoot, etc. They will all spray and stink up the place. My gun of choice is the 12 gauge with #4 or larger shot. Less chance of just wounding it. Although a 22 will work just fine if you are a good shot. Of course this depends where you live and how close your neighbors are.
Good Luck!
Dodgeman