The room, setup, and placement are huge factors. Assuming the gear is good, and cables aren’t the weak link, speaker placement is typically low hanging fruit. I tend to use the music I listen to most as my reference, at least the ones that are decent recordings. Some recordings have more bass, some less, so it’s good to find a happy medium with the stuff you listen to most often.
Isolation of your gear is another subtle way to optimize things, and squeeze a bit more refinement....TT, amps/pre, speakers. TT and preamp are on sorbothane feet. speakers are on isolation spring pucks, amps are on rubber/cork feet.
I tend to use tube rolling and cable changes for final tweaks to dial in the sound I want. There are really no hard fast rules....it’s very subjective, and very unique to your setup, so you have to experiment a bit.
Once I was pretty happy with the overall balance, presentation, and synergy is about the time I started upgrading power supplies and opamps in my DAC and phono stage for a bit more refinement. Wall warts got replaced with linear regulated power supplies.