Steps to repurpose old laptop as home server with Debian - eviltoast

I have an old ThinkPad 11e running Debian that I have repurposed into a home server. It’s only supposed to run TVheadend. I don’t need any other services for now, but later on i might add a few using docker.

Is it enough to set multiuser.target as default to disable gui and keep the system always on?

How can I disable all unnecessary services and minimize power usage?