Our basic and favorite dry rub for pork goes something like this...

Here is what you need:
1/2 Cup Light Brown Sugar
1/4 cup Paprika
Tablespoon Black Pepper
Tablespoon Chili Powder
Tablespoon Coarse Salt
Tablespoon Garlic Powder
Tablespoon Onion Powder
Teaspoon Cayenne Pepper

You can make adjustments depending on your tastes, but this is a common setup, and a good place to start. Mix it up good and then apply a generous coat to the entire surface of the meat. You can use a shaker to apply, or just rub your meat by hand, whichever you prefer... Opinions regarding how long you should leave the rub on the meat also vary widely, some say leave it on for hours, even overnight, others say put it on just before you start the cook, which is about where we are (we apply the rub about 15 minutes or so before the meat hits the smoker). I suspect there is no wrong way really, so feel free to do your own thing.