“How horrible it would be . . . if she were condemned to be the plain, shy Millicent of a few years back.” - Direct characterization. The speaker explicitly says that Milicent now isn't plain and shy, and that would be a condemnation to her.
“Betsy Johnson, the vivacious blonde secretary of the sorority” - Direct characterization. We can see Betsy and we get some information about her character (vivacious).
“Walking beside Louise on the way to the drugstore, Millicent felt a surge of pride.” - Indirect characterization. The speaker doesn't say that Milicent is this or that kind of person. He/she just puts her in a context, commenting on her current feelings and thus allowing the reader to make a vague conclusion about her character.
“Bev was suddenly there in the doorway. ‘Wipe that smile off your face,’ she commanded.” - Indirect characterization. Again, the speaker here describes this character's action, rather than features and character traits.