Paying attention to all the details. Simple things like is the turntable level? Are the speakers in phase? Is everything properly grounded? Set up is everything. Don't just consider the little things like the wires, the cartridge, or the isolation devices, the elephant is...the room itself. And don't forget that furniture matters. Leather reflects, textiles absorb, a carefully placed bookshelf can be a great aid to acoustics, but a big coffee table in the wrong place can really screw up the sound stage. Like I said, pay attention to all the details. It doesn't hurt to have a sympathetic significant other.
My Favorite Tweaks, What is yours?
My favorite tweak is Puron lowering noise floor of my system. Holostage they open my system more, bigger soundstage , improves layering as well ,and made my system more effortless to listen.