If the command zone you want to place your command vehicle in only has one small area forest, do not put in that area. Experienced players will most likely blind fire that patch of forest with artillery in the hope of getting an easy kill.
A good tactic is to have Self Propelled Anti-Aircraft Guns (SPAAGs) guarding your command vehicles, as they will deter enemy aircraft from getting too close as well as destroying light ground units and infantry. This being said, it is better to not have your SPAAGs positioned too close to the vehicle they are guarding, as they will draw enemy artillery fire.
If a command zone you own is bombarded and the fire is no where near the command vehicle, move your command vehicle. This will trick the opponent into thinking your command vehicle was near the hit area, basically giving them misinformation.
If you are evacuating a sector, always make sure the command vehicle is evacuated before any other units as it is worth a high number of points to the enemy.