I use the KISS method. 1c k.salt, 1c surgar(usually brown), 1 gal water. When adding spices I heat up whole spices in a pan then put in water. Stir well and add salt/sugar slowly and it all disolves.
I only brine birds for about 6-8 hrs and I don't worry about skin as we just dont' eat it, probably cause I smoke the birds at a lower temp and suck at getting crisp skin.