I installed JIRA last year but haven't ended up using it a lot, so I thought I'd stop it from starting automatically at boot. This wasn't immediately obvious how to do as the service command doesn't have that option.
This seems like a pretty definitive answer, but I ended up going with sysv-rc-conf as it seemed kind of easy to use and visualise everything that's going to be started.
The initial state for JIRA looked like this:
By unchecking everything, it no longer starts up by default: