Good artillery observers are valuable assets which have to be protected and therefore exposure has to be kept to a minimum.
It's wise to give a small Target Arc to your observer so that they don't fire at some opportunity target, and thereby reveal themselves.
Observers need positions with sweeping line of sight. The best positions are those with covered or concealed approaches. When moving from out of enemy line of sight into it, you can avoid enemy spotting by using Slow (crawl) for the last bit of the move. For example, when a unit moves to a hedgerow a distant enemy on the other side will see nothing until the unit is right next to the hedgerow. So you can move Quick up to the action spot next to the hedgerow, then crawl the last 4 meters.
While calling for artillery, the following sequence of action helps minimize exposure to enemy fire:
- The observer needs a clear line of sight to the target action spot when making the initial call for the mission ("Requesting Fire Mission"). So give the fire order for the assets you want to use.
- While transmitting the orders (between the Request and the end of the "Preparing" Phase of the asset), the observer does not need to see the target for several minutes. Thus you can hide the observer or even move it back into good cover. (The delivery time in the HUD area with the mission parameters should give you a good indication when the first spotting round will be delivered.)
- The observer must see spotting rounds hit to adjust the fire. Thus, as soon as the "Spotting" phase starts for the asset, you need to have your FO back in the observation position.
- After "Fire for Effect" has begun you can hide or pull the observer back again.
With this approach your observer will be exposed only during the moment when requesting the fire mission and during the spotting.