Unfortunately, the task seems way too daunting. How can one teach common sense?
Just like parents explicitly say their expectations of tznius, kashrut, etc, you can do it about financial things and the way things are done in your family, without being derogatory of others.
My kids know I have a "hashkafah" about money, not ever paying with a credit card if I can't pay it off fully, choosing not to buy a new car until I can pay for it in full, etc. Again, never demeaning others but explaining what we do and the comfort and freedom it provides us.