The first step in smoking a barbecue chicken is to find a good chicken. Don't pick up a shriveled, frozen bird at the supermarket. Pick out a fresh, plump bird, and avoid any chicken that is packed with "solution". Many chickens these days are mixed with a chemical brine to make it look good and plump. This makes them look good, but doesn't make them taste good. You want a good size because it's going to go fast. If you're cooking for more than about five people consider getting two. I usually try to find a 4 to 5 pound bird. Yes you can find them. If you can't find a fresh one, then follow the instructions for thawing.
Smoking one 4 pound chicken will take about 4 hours. Before you put the chicken in the smoker give it a good wash and trim off any lose fat and skin. Smoke at about 220 degrees F until the temperature at the center of the chicken breast reaches about 185 degrees F. Watch this temperature closely because you don't want to get to far above 185 degrees F.
If you do nothing with the chicken at this point but put it in the smoker you'll get a marvelous bird. However there are several things you can do to add additional flavor to this chicken. The low and slow method of barbecue produces a vastly superior chicken to grilling. Smoked chicken is easy whether you use a large offset smoker or a charcoal grill. This is a great recipe to start with if you are just learning about barbecue.
My favorite barbecue mop recipe is a good stout. I usually get a really big bottle of stout; use about 1/4 for the chicken and the rest for me. Pour some beer in a bowl; add some garlic and onion, maybe some sage, thyme and bay leaves, or cayenne, chili powder and paprika. Of course there are lots of great smoked chicken recipes out there.
For poultry a good barbecue rub usually has sage, thyme and bay leaves. These flavors go along way with chicken. You want to work the spice rub all over the chicken. Get it into every nook and cranny, including under the skin where possible. Try to harmonize your flavors by using the same combination in your rub or mop.
So how do you know when the smoked chicken is done? Use a thermometer. It is the best way to know that your bird is safe to eat. Chicken is cooked at 165 degrees F but when smoking you want to over cook it. Look for a temperature around 185 degrees F. Test the temperature in the thickest part of the chicken breast. A good smoked chicken will be very tender, have a late summer tan, pink meat and the juices will run clear. Make sure your bird has all these elements.