I hear ya. It’s not a terribly common consonant cluster. (In fact I think all English words that start with s[c]hm are Yiddish loanwords, but don’t quote me on

I hear ya. It’s not a terribly common consonant cluster. (In fact I think all English words that start with s[c]hm are Yiddish loanwords, but don’t quote me on that.) Try pushing your lips forward before making any sound, and drawing them back+together as you make the sh sound. It’ll come out as a single shm sound.