There is a moment in every homelab where the pile of gear on a shelf becomes a proper rack in the garage, and you feel briefly like a serious person. I had that moment. I also have the regrets, so here they are while they are fresh.
The garage was a mistake on temperature alone. Summers cook it, winters chill it, and the hardware notices both. A rack of spinning disks does not love a cold start at three degrees any more than it loves baking at thirty. I now run a cheap temperature sensor that pages me, which is treating the symptom rather than the cause, but moving the rack indoors is not a fight I will win with the household.
The other regret is noise I never planned for. Those 1U servers move air with tiny screaming fans, and the garage shares a wall with a bedroom. I have since swapped the loudest offenders for quieter kit and the family has forgiven me, mostly.
What I got right was buying a deeper rack than I thought I needed and labelling every cable on the day I plugged it in, not later. Later never comes. If I started again I would put it in a cupboard with airflow, not a garage with weather, and I would have run the numbers on power draw before the first electricity bill did it for me.