I like brining pork butt before applying the dry rub, so in case you're up for that, here's how to do that.
About 8 oz. kosher salt to 2 quarts of water, maybe 2 oz. less if you're using table salt.
6-8 oz. sugar and I like using brown sugar
a couple Tbls whole peppercorns
Make sure the salt & sugar are completely dissolved and immerse the pork in a ziplock bag with the brine and I usually let it go overnight, so let's say 12-24 hours.
Remove the pork and pat it dry, let it stand a half hour before putting on the rub.
Here's the rub I use and note it should be to your taste, so these are only guidelines.
Aprox 1/4 cup paprika
1-2 Tbls granulated garlic
1-2 Tbls onion powder
About 1/4 cup brown or white sugar
2 Tbls cracked pepper
About a tsp to start of cayenne, and more if you like the heat
Note that this is an excellent rub as it stands, but I like to add about a Tbl each of cumin & chili powder
Mix thoroughly and alter to your taste
Apply the rub all over the pork, pressing gently to make it adhere, and let it stand a half hour to settle in before BBQing.
Hope you get a terrif BBq, you should!