Ingredients

2 tb salt
2 tb sugar
2 tb brown sugar
2 tb ground cumin
2 tb chile powder
2 tb freshly cracked black
1 pepper
1 tb cayenne pepper
4 tb paprika

Instructions

The rub is the second most important part of the BBQ process, next to
the smoking technique. There are two main concepts to keep in mind
when formulating your rub. The proportion of salt should be great
enough to trigger osmosis and begin to draw the moisture from the
surface of the meat, and (some may disagree with this) the proportion
of sugar should not be excessive because it will caramelize and burn
during smoking leaving a bitter taste. However, since sugar
contributes to osmosis, it is an important component and shouldn't be
eliminated.

Beyond that, your rub should only be limited by your imagination.
Other ingredients to consider can include paprika, cumin, garlic
powder, onion powder, black pepper, cayenne pepper, chile powder,
oregano, sage or whatever sounds good to you.

I like to keep my rub in a shaker for easy application. Rub should be
applied at least the night before smoking. Anything longer, up to
three days, is better. Shake the rub over the entire surface of the
meat to be smoked. Use a generous amount at first and then, as it
starts to get moist and adhere, add more. I don't think it's
necessary to "rub" it in. I find that that only results in uneven
distribution, and besides, it stains your hands. Wrap the meat
loosely in butcher paper and leave in the fridge until a couple of
hours before smoking.

I find rubs to be far more useful than marinades especially for large
pieces of meat such as briskets and pork butts. For cuts such as
these, the internal and external fat melt through the meat during
cooking to keep it moist. I believe that the texture of the meat is
improved by drawing out excess moisture, before cooking, through
osmosis. The dry surface of the meat and the rub itself combine to
produce a flavorful and attractive crust on the finished product.
Unless it is thoroughly blotted dry on the surface, marinated meat
won't color properly.