Notice good behavior.
It is SO easy to see all the ways our kids need "gentle correction," whether it is coming inside with muddy shoes, or leaving their book bag on the kitchen table, or squabbling with their sibling.
But do you notice the good things they do? Are you glad they played outside and got some exercise (instead of just sitting in front of the TV or computer)? Do you compliment them for being faithful to do their homework without your even asking?
When you praise your child, make it specific. Tell him or her, "Thanks for mowing the lawn. You did a very careful job even around the bushes and trees. I noticed you even put the mower back into the shed! Thanks so much." You may even give a special unexpected reward such as, "Here's money to ride your bike to the corner market for an ice cream." Better yet, take them there and enjoy one together!
As they say, "You catch more flies with honey than with vinegar." Lasting positive change is the result of positive reinforcement all along.
"Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen" (Ephesians 4:29).