I use the YIVO Institute For Jewish Research standard. According to their "rules" you always use "sh", never "sch" ("shul" not "schul", "farsheyden" not "farscheyden", etc.).You also always use "kh", never "ch" and "ts", not "tz".
That's what I've been taught and I'll stick to it!
Unfortunately, the ugly truth is: I am prone to mixing up the Yiddish and the German orthography. Di shande!
And I have to admit that I use the "Eisenstein Method of Spelling" a lot: Whenever a word looks too German I doubt it's spelled correctly... mentschlekhkeyt / Menschlichkeit.
Maybe I will become the yidishe vintzok? "LEMAY? LEMAY? LEMAY???"
Hey, but I speak flawless Donnylongese: Oogaahh! Grunt!
Rediscovering your cultural heritage is a bitch... But it's worth it! Coming soon: Luca Avishai Eisenstein tries to learn Hebrew, goes cuckoo and "speaks in tongues"...