Parents should be strict about who their children are spending time with (eg.) friends they have, babysitters, etc. depending on the age. Also be strict about respecting adults- particularly authority figures. Children are failed by this not being enforced and grow up with no sense of integrity. Respect for others builds character.
i am not a parent i am actually 15 but my neighbors discipline their children by making them do push ups and workout instead of yelling and grounding and their children are very well mannered but your kids need to be used to working out or they need to get used to it.