Smoking meat is different from grilling. Smoking consists of cooking meat low and slow. ideally over hardwoods such as hickory, oak, or mesquite.
Smoking is true classic barbecue, a method of cooking that renders down fat and breaks down the collagen that makes meat tough. It will turn a cheaper and tougher cut of meat into a delectable morsel!
A great tip for ribs and pork loins/tenderloins is to coat the meat with yellow mustard, then apply the rub. You won't taste the mustard but the vinegar in it acts as a tenderizer, and it holds the rub onto the meat and helps create a great crust.
Direct vs. Indirect
Generally the indirect method is preferred for longer smokes. When you smoke indirectly the meat is not directly over hot coals or flame, but either to one side of the coals or with a plate setter or pizza stone between the meat and the coals, often with a drip pan between.
Offset smokers are designed specifically for this but are known for difficulties controlling temperature. If you have a regular charcoal grill such as a Weber kettle, simply start your fire as described here and then spread the coals to the outer edge of the grill and place the meat in the center.
Most gas grills have 2-4 burners so indirect cooking is very easy. Simply light one or more burners and place the meat over the unlit burners. For smoky flavor, you can wrap soaked wood chips in aluminum foil and poke holes in the packet with a fork or use an inexpensive smoke box.
Smoking meat adds that savory taste and decadent aroma that defines barbecue and can be provided from the base fire or by adding lumps or chips of your favorite woods, even to gas grills and indoors as well. Look here for more information.