I'm fairly new to smoking and today I made my second attempt at beef brisket. It came out dry and tough, luckily I had some turkey and sausage in with it and they both turned out great. My first brisket turned out dry as well. The brisket was about 4 lbs which is small and I smoked it at a steady 225 for 6 hours until the IT was 165. The day before the smoke I applied rub, wrapped it in plastic wrap and put it in the fridge. The next day I added a little bit more rub before putting it in the smoker. Do I need to go with a bigger brisket? Could it be the rub that I am using (pre-made stuff I bought at the store)? At this point I really don't know what I am doing wrong. I am Phoenix, AZ which is a very dry climate. Could this be impacting my brisket? Any suggestions would be much appreciated.