Miss Maudie Atkinson. Maudie gives Scout lots of good advice throughout the novel. She explains why "it's a sin to kill a mockingbird"; why most of the gossip about Boo Radley is untrue; and why pulling up nut grass will only spread its seed--it must be poisoned instead.
Miss Stephanie Crawford. Scout's neighbor advises her that "you won't get very far until you start wearing dresses more often," but we know (from the first page of the novel) that Scout turns out all right as an adult.
Atticus. Atticus explains to Scout that it is "common" to use the "N" word. He advises her to stay in school, and to be patient with her new teacher, Miss Caroline, since it wasn't really fair to judge a person "until you climb into his skin and walk around in it" first.
Aunt Alexandra. Scout's aunt makes it clear that Walter Cunningham Jr. is not fitting company for the Finch household. Alexandra tells Scout to treat him politely, but that, in truth, Walter is "trash." Scout disagrees. She believes Walter is like most people: just "Folks."
Calpurnia. Cal advises Scout that it's not "ladylike" to act superior around people. "It aggravates 'em."
Jem. Jem advises Scout that if "you antagonize Aunty... I'll spank you." Jem's advice to not deliberately anger Alexandra and stay out of her way was good, but his threat only provoked Scout to "grab his front hair and land one on his mouth."