Azimuth 2020

There you go, Lewm has the right idea. You put the stylus down on a pocket mirror which makes the error much easier to see. Use a good light.
The stylus and it's refection form an hourglass. You adjust the azimuth until the hourglass is perfectly symmetrical. There is no better way to do this as this insures the lowest record wear. If the cartridge is not constructed well you might have more crosstalk but the solution to this problem is not more record wear. It is a better cartridge. 

edwyun, I ask this question out of pure curiosity, not meaning to disagree at all, but is it possible to optimize two parameters (crosstalk and phase) that may be antagonistic by making one adjustment of cartridge orientation (azimuth)?  I would guess the result is inevitably a compromise, which is where we all end up in this hobby.

Unwarranted to disagree with anyone here. Civil discussions are pleasant AND educational. Thanks all for the insight.

you can not use a pocket mirror for azimuth.  The silver (reflective) side is above the glass its sitting on which will create big errors.   If you must use a mirror, get an old SLR camera mirror that is silvered on the correct side for your application.

Fuzztone,  I find it's most enlightening when two or more people openly disagree and then have a civil discussion, preferably backed up by facts in support of one position or another.  It's fine to disagree, in my opinion.  It's better not to be nasty about it.
Stringreen, I did not want to be needlessly contentious with Mijostyn and others who have suggested using a mirror.  I personally do not.  Also, I never finished explaining my rationale for deciding not to agonize over determining azimuth electrically vs setting it "physically", by setting the stylus square in the LP groove.  It's because in the electrical measure, if the stylus ends up at an angle with respect to 90 degrees azimuth, then you may (or may not, if you haven't done it correctly) have better numbers for crosstalk, but you have introduced other sources for distortion and possibly sources of wear on the stylus, suspension, and the LP.  That scares me more than a small deviation from the best possible numbers for crosstalk.  If the cartridge is poorly constructed such that the azimuth angle has to be other than 90, send it back.  (I've never tried to do that, because I never had the foresight to measure a brand new cartridge just after receiving it.  Also, most of  the cartridges I own are vintage.)