I think one of the most important sysadmin jobs is learning where the logs are, which ones are important, and learning to monitor them. There are likely app logs, web access logs, sshd logs, general syslog logs, etc., and it's good practice to understand them and to know what is normal and what should be investigated.
A good way to get started is to install something like tmux or screen, then run "tail -f " to start watching. It sounds simple, but in a crisis (which maybe doesn't apply to a hobby project), separating noise from signal is key.