Start with the business process
When a central server fails, a department mainly wants to know when work can resume. Restoring a machine is only part of that answer. Sign-in services, data, network connections and dependent applications must also be available. Start planning with a specific business process. Which people need which functions, and in what order must the supporting information become accessible? This view reveals dependencies that are easily missed in a list of devices and installed software.
Agree objectives together
Decide with the responsible people which interruption and potential loss of recent data the process can tolerate. These decisions inform backup and recovery requirements. A broad statement such as as quickly as possible is not enough for a dependable plan. Distinguish the desired objective, the technical procedure and the result actually measured. A rehearsal helps reveal missing prerequisites and steps that take longer than expected. Record the assumptions behind the plan so that others can assess them.
Prepare a safe rehearsal
A recovery exercise needs clear boundaries. Identify test data, the destination environment, responsible people and stop conditions. The exercise must not overwrite active systems accidentally or start duplicate services on the production network. Check beforehand that necessary credentials and installation information are available through the intended secure channels. Define the functions that will be checked after restoration. An operating system that starts successfully does not by itself show that the department can resume its actual work.
Turn observations into improvements
Record timings, obstacles and test results. Small observations are often especially useful: a missing permission, unclear ownership or an instruction that only one person understands. Assign an owner to every unresolved item and check the improvement during a later rehearsal. NIST describes contingency planning as a coordinated combination of procedures and technical measures. In a business, that becomes a repeatable way of working which does not depend entirely on the memory of individual administrators or on one person being available at exactly the right moment.
Further reading: NIST: Contingency planning.