After your initial panic, it's important to remember that a significant component of your survival is the demise of the ghouls trying to get your tasty brains. (omnomnomnomnom) The only way to permanently "re-kill" a zombie is to destroy its brain. This isn't rocket science (although that would be a cool way to do it!). A gunshot to the head is the most direct way to disable a zombie, but not the only way. Decapitation also works, although the head will probably still function so don't let it bite you.
If you survive long enough, and society collapses along with any hope of rescue, you'll need to develop some means of skull penetration that doesn't involve guns - a professional bow hunting setup works if you can get it (see where archery class you always hated comes in handy?). You might be squeamish at first, taking out your neighbors, but not to worry, with time this will pass, and hey! you might even adapt some sort of sick horror-movie-worthy humor about it.
