"Let's assume already pretty high level of both."
Alignment Tools and Skills: acquire the few inexpensive tools and learn to do it yourself.
Go beyond: Think long, think about options, flexibility, it took me over 40 years, retirement, and rethinking everything during covid, and a lot of help here for this.
The great unknown, who knew my friend would leave me his collection of over 4,000 LPs, mostly Jazz, many played only once.

Stereo/Mono/MM/LOMC/MI, I'm a big fan of two tonearms, Stereo and Mono aligned, calibrated ready to play in an instant, combined with a small collection of cartridges pre-mounted in headshells with azimuth adjustment, and easy adjustable arm height.
If you have one darn good cartridge, with an advanced stylus shape, even on basic aluminum, it is good enough to find and settle on a MM Phono stage. Get that DONE.
to me, my Tube MM Phono is done for life, as is my SUT, to pre-boost LOMC so I can keep using it.
I have added other new cartridges, taken risks with used Vintage otherwise unobtainable cantilever materials, and enjoy listening to friend's cartridges they bring here.
We all have Steve and Ray Leung at VAS and Peter at Soundsmith to expand the possibilities, including purposely buying broken cartridges.