Duh! That's all that we have to work with here, so of course speech and dialogue are major characterization tools.
Mom's speech characterizes herself more than it does Girl. After all, how can she tell Girl about these things if she doesn't know about them firsthand? Since she knows "how to bully a man, " and "how a man bullies you," not to mention, "how to love a man; and if this doesn't work there are other ways, and if they don't work don't feel too bad about giving up," we can assume Mom has had some difficult times with the men in her life.
And why would she be so worried about people judging Girl if she weren't a little bit of a Judgy McJudgerson herself?
Okay, Mom is obsessed with the idea that Girl is going to become a slut. Want proof?
• "on Sundays try to walk like a lady and not like the slut you are so bent on becoming" (10)
• "this is how to hem a dress when you see the hem coming down and so to prevent yourself from looking like the slut I know you are so bent on becoming" (17)
• "this is how to behave in the presence of men who don't know you very well, and this way they won't recognize immediately the slut I have warned you against becoming" (33)
• "you mean to say that after all you are really going to be the kind of woman who the baker won't let near the bread?" (53)
Okay, so the last one doesn't specifically say slut—but it sure is implied.
So what is a slut? A slut is someone who doesn't walk "properly," someone who doesn't take care of her clothes, someone who doesn't act "properly" in front of men, and someone who the baker won't let near the bread. In other words, someone who doesn't do the things that society says are "proper" and "important" to do, and so is rejected by society.
That might not be the definition you'll find in the dictionary, but if you think about it, that's basically how the word works. (Oh, and fun fact: "slut" originally meant a woman who was messy and untidy—it had nothing to do with sex.)
So, a slut is someone who has the lowest social status and gets booted out of society because she doesn't do the right things, or does the wrong things (or the wrong people). That's exactly the fate Mom is trying to keep Girl from experiencing.
On the other end of the spectrum, Mom's list of actions is basically the outline for the "Good Lady." A good lady knows all the things that Mom is talking about. She knows "how to make doukona" and "how to make pepperpot" (39-40); she knows how to "set a table for dinner" and how it's different from "how you set a table for dinner with an important guest" (29-30).
Doing the right domestic actions makes you a good lady. Doing the wrong ones? Well, you know.