1. If you have lost visibility, you've lost accountability. 
2. If you find yourself in heavy smoke from ceiling to floor, ask yourself if you would be in this position if smoke were called gasoline.
3. Ventilation doesn't always equal cooling.  Sometimes it causes the fire to accelerate or even explode.
4. If you arrive on scene and only find smoke showing, don't feel a sense of relief.  Ask yourself if you are early in the fire progress or so late that the fire only needs oxygen.
5. Fighting fire from the unburned area to the burning area doesn't always make sense.  (Ie. if the fire grows exponentially while you put the line in place or you have a sealed compartment (stonegate, LA County-Sharpiro video, etc.)
6. Ventilate from the top down.  (Charleston)