Welcome to Forum, I think you will find this is a great site for tips and recipes here, and a great group of people. Every one of us have our own method for pork shoulder and everything else. Mine is pretty simple. I'll post mine here for you to look over for a starting point.
Before finding this site most of my smokes seemed to be tough and dry. I always thought I was over cooking. Wrong. I was not cooking near enough, I was trying to smoke by time, not Internal Temperature, which is virtually the only thing that matters for tender meat.
I smoke PB's (and briskets) in a Smoke-it brand electric at 225, low and slow, works for me. Put some rub on it. Put it in the smoker, set the remote IT probe beeper at 195, turn it on and forget it until the beeper goes off. Sometimes at 12 hours, sometimes at 26 hours later, depending a little on size, but mostly on the particular chunk of meat. Every chunk is different. Most 12-15lbs will be 18-22 hours for me, but I never know. Be prepared for the "stall" somewhere about 170. It can sit there a couple of hours at times before taking off again.
Then at the 195 beeper, because each piece of meat is different, I poke it with a instant read temp probe. ($20 at Lowe's) Gives me a feeling if it is done like poking butter or needs more cooking along with giving me a cross check of IT temps in other parts of the chunk. Need a little more sometimes, a lot more most times. I check it again in 30-45 minutes, repeat till done. 200 or 205 is not all that unusual..
After I get it where I want it, I wrap in foil and put it into a towel wrapped ice chest for least a couple hours before pulling or slicing. Because of unexpected circumstances I had to leave one almost 5 hours once, it was still steaming hot while pulling.
Check out some of the finishing sauces for pulled PB for an even better flavor. We like extra smoke, usually after pulling I will put it in a couple open foil pans and put those back in the cold smoker and add extra smoke while it is warming up for about 20 minutes, then re-mix
Good luck to you, and let us know how it works out. Every smoker is a little different just as all of our taste buds are a little different at different times...Keep fine tuning and trying different things.
Good luck to you.