Don't diss rich relatives unless you're independently wealthy. (S&S, uh oh, Willoughby; P&P, Darcy can diss whomever he likes.)
If your girlfriend puts your most deeply held convictions down, she's not for you despite her sparkliness. (Mansfield Park)
If you're trying to get one girl, don't screw her cousin. (Mansfield Park.)
You're not as clever as you think. (Emma, re Frank Churchill.)
Walking everywhere instead of riding in your carriage like a gentleman will give you great legs and glutes. (Emma, re Mr. Knightley.)
Catching large falling objects, like girls, doesn't always work out. (Persuasion, ouch.)
Don't walk off with your sister's book -- she'll never forget it. (Northanger Abbey.)
Don't propose in a letter, especially when your intended has busybody friends. (Emma.)
Don't make snide remarks about a girl when there's any possibility she'll overhear you. Especially when she can run rings around you, sarcasm-wise. (P&P.)
Steady and sturdy affection may win out over glitz in the end, but only if the girl gets a really bad cold. (S&S.)
Living beyond your means/gambling: These habits really suck. (S&S, Mansfield Park, Persuasion, P&P -- but Trollope is the champion at pounding this truth home.)
Make sure you don't marry a pretty but silly woman, unless you're pretty and silly, too. (P&P; S&S re the Palmers; Mansfield Park, though Sir Thomas seems to have reconciled himself to Lady B.)
