The ingredients for the baste depends on your preferences. I usually set aside a tablespoon or two of the rub and mix it with two tablespoons of melted butter and two tablespoons of olive oil. The butter and oil will give the turkey a shiny appearance and add some moisture to the skin (which probably looks a little dried out at this point). In addition, adding some sweet to the baste gives the surface of the turkey a candied flavor. I dissolve a tablespoon of dark cane sugar into the melted butter. Since our cooking temperature is low the sugar won't burn, but watch to make sure that the temperature doesn't rise far above 165 degrees F (the burning temperature of sugar).
Apply the baste on to every inch of the surface of the turkey, including the insides. If you want to do a lot of basting, double my recipe and repeat after 30 minutes, giving the first coat time to sink in.