For Op. 60 no. 2, when a note is on the string 3, use p. When notes are on strings 2 and 1, alternate between i and m. You should choose which finger to start an alternation sequence by looking for "good" string crossings.
It is not always possible to have only "good" string crossings. Our goal should be to find the most "good" string crossings and limit the amount of "bad" string crossings.