There's dozens of directions you can go with turkey breasts. But I like to keep the rub simple so the turkey tastes like...turkey.
Just mix up a some Lawry's seasoning salt with a few grinds of black pepper. Add a pinch or two of cayenne until the rub has the bite you're looking for. Sprinkle the rub all over the meat and work a little under the skin. Then, smoke with pecan or a mild fruit wood until the internal temperature reaches 160 -165. Remove from the heat, cover and rest for 10 minutes.
Your nose and your belly will tell you what to do after that.