A good way of identifying them is to adopt the viewpoint of the enemy commander, what would paralyse him? Also worth noting that they occur at every level of warfare.
Say at the Tactical level, the COG/CV of a force is usually its leader, its supply train, or a geographical feature (we'll come to those in FS when I post up the second part). At the Operational level, they are what make an Army's position untenable, so usually its command staff (what would happen to the GTVA force in Sol if the UEF eliminated Steele? What if the Shivans nailed Petrarch? Or 3rd Fleet Command?), its supply train, geographical positions such as choke points, etc. At the Strategic level, we look at what would paralyse the actor. Leaders, capital cities, and the dominant ideology are all good places to start.
Also I have to apologise, I've got a mild-moderate peanut allergy and have made the mistake of letting my friend buy me a kebab without realising the satay sauce had peanuts, so whilst not incapacitated obviously, I may not be able to submit anymore substantive material tonight, but I'll do my best!