Before any reference to MusicTEX macros:
normalshapemediumseries\input musicnft
normalshapemediumseries\input musictex
which may be followed by normalshapemediumseries\input musicadd
in the case you have more than six instruments (voice is two instruments: one
for the music, one for the text) or more than 6 simultaneous beams or ties or
slurs.
After that, you may write a complete book of TEX provided that
you do not use normalshapemediumseries& as a tabulation character (its
normalshapemediumseriesnormalshapemediumseries\catcode
has been changed) inside the music score and that you do not overwrite
MusicTEX's definitions. This means that no special macros have been designed
to help you write titles, author names, comments, literature excerpts, etc.,
unless you use LATEX with the musictex style.