At what stage and what exactly should be checked first when setting up a monitoring system?

When setting up a monitoring system, the following points should be checked first:

1. Availability and correctness of metric collection — ensure that monitoring agents correctly collect data from the necessary services and hosts.
2. Alert configuration — verify that threshold values for notifications are adequate and do not cause false alarms.
3. Data visualization — make sure that dashboards display key metrics and allow for quick assessment of the system's state.
4. Integration with notification channels — check that notifications reach responsible persons (e.g., in messengers or email).

It is advisable to start with checking data collection, as without correct metrics, the other stages are meaningless. Then proceed to alert configuration and visualization for convenient monitoring.