Monitoring is inmensely important so to ensure the liveness and reliabilty of your infrastructure. If your validator is not signing blocks it will eventually get slashed losing you and your delegators some of their SCRT balance. Same for full nodes it is important they are able to serve queries as if they are down performance of dApps and other applications will be limited.\
Monitoring is best done by a dedicated piece of software that provides both analytics and alerts. Some of those options are laid out below so to help you set them up. Consider relying on more than 1 monitoring solutions and leverage external RPCs so to secure your setup even further.