hi, core cycle
here's how i do it - others will come along and tell you how they do it. read up on different methods and decide which is right for you.
the night before i do a shoulder (picnic or butt), i brush on a light film of plain, yellow mustard. your pork will NOT taste mustardy when this is all over, but the mustard does aid in the rub clinging to the meat and in my opinion creates a better bark - and you will love bark.
anyway, after the mustard, apply a liberal amount of your favorite rub to all surfaces of the meat. you can use any rub you want, but i recommend one that:
a) has paprika for a nice, rich, red color
b) has a minimum of salt (this is mostly for health reasons but also because if there is too much salt you lose a lot of the other flavors)
c) has eithier a small amount of sugar, no sugar or turbinado sugar (sugar in the raw) instead of white or brown sugar. this is because a shoulder takes a long time to cook and somewhere in that time the sugar will go from a beautiful carmelized brown to a very ugly black that tastes fine but looks terrible.
wrap the pork shoulder in saran wrap and refrigerate overnight. to me, it's best for it to sit overnight in rub, but the world will not end if it doesn't. even if you slather and rub it right before it goes on the grill, the world will not end.
before firing up your smoker (it will take time to come to temperature), take your shoulder out of the fridge and let it set for a while, but not more than an hour, to come up a bit in temperature. i prefer to take my straight from fridge to smoker, but i don't recommend this unless one is fairly experienced with good fire tending as creosote formation is a danger. anyway, unwrap your shoulder and, if desired, apply a little more rub all around, then toss it on the grate as your smoker temperature is passing 225 degrees.
smoke over your preferred wood at between 240 -250 degrees until you can twist the bone right out of there (this could take a very long time, so allow yourself at least 12 hours. it may not take that long, and it may take a little longer, but if you allow 12 hours, you should be in good shape.
you are shooting for an internal temperature of about 195-205 degrees. when this temperature has been acheived, double wrap the shoulder in foil, wrap the foiled shoulder in towels and place in an empty cooler for at least a half hour. you can leave it in for as long as 6 hours or as long as the internal temperature is above 140 degrees. this allows the meat to rest and the juices to pull back into the meat. it might also be handy in case the shoulder is ready before it is time to eat. let it rest at least a half hour before removing the foil or your meat that you worked so hard on will lose its juces and turn an ugly brown color.
when the resting time is done, open the foil and it will pretty much fall apart and be VERY hot. pull the meat apart with your fingers or use a couple of large forks raked across it to shred it to your desired consistency. remove any gristle, fat etc. at the same time.
serve on a plate or on buns using RIVET's outstanding east-carolina finishing sauce. some mix the sauce into the meat, others just pour some on top of the meat as it is served, your choice.
i am at work right now, but rivet can post his sauce or i can post it tonight.
i guarantee results if you do it as described above, but i will stress that the above method is not the ONLY way to do it.
good luck, let us know how it goes and take pix!