Most smaller smokers are designed to use a heat source that is not logs of wood. Be they electric, gas or charcoal fired, they are characterized by a small fire box/heat area.
Neglecting electrics for a moment, heat sources require air. Stuff does not burn without it. It also burns too well with too much of it. Airflow is the key to all smokers' temperature control. Sure less fuel/flame can be used, but the dampers are an indispensable item, especially with charcoal fired smokers. With the gas units, airflow is more related to smoke quality alone, as opposed to heat and smoke in a coal unit.
The idea of the damper is to allow enough air to maintain heat and yet keep things from becoming an inferno. Also, realize air has to LEAVE as well, so units that have a "stack" or "exit damper" need to have those adjusted as well.
For charcoal type units, lump style charcoal is the best to use, offering more heat and less ash production then the formed "briquette" types. "Bricks" CAN be used, but are not the preferred type.
The idea is to get a good bed of hot coals going, and add wood sparingly to produce the ideal "thin blue smoke" that is going to flavor the meat without overpowering it, or depositing creosote and other nasties on it.
Another thing that really helps is a "coal basket". This is usually just a welded or bolted together expanded metal type holder for your charcoal. It allows much better airflow and therefor better burning characteristics for these units, and also helps keep ash from choking off the coals.
Larger units- stickburners- use the same principle. Some use "weedburners" to get them going, some use a "burn barrel" to create hot coals for the firebox. Lump charcoal can also be used as the bed and wood placed on top. I will caution some of the mid-sized side firebox folks... you probaby don't have a "stickburner". You would be better off with the lump charcoal for heat and wood chunks. With enough experience you may get good results with wood only, but it will take some playing around to get it right.
Now, electric units- "Wattburners" and a bit different. Chips or sawdust is usually placed in a pan on or very near the heating elements to create the smoke. Small amounts of them at that..
Basic's information was contributed to Smoked-Meat by Pit Master Richtee