Yo so asking for a friend, how does one enter a mirror??

step 1: find your mirror, gotta be a nice one, you don't want to feel cramped once in there.
step 2: find a witch
step 3: befriend the witch
step 4: tell her your wish, prepare something in return (best bet is to seduce them with food)
step 5: be the mirror person you were born to be