Speak once, in love, in normal tone of voice. Then expect them to obey.
Love must be your motivation! When you reprove, have your attitude under loving command, speak firmly, yet with gentleness and tenderness. Loving correction begets loving responses.
Make sure that your children understand their sin - not just their actions. Get at the attitudes behind the actions.
Talk to them. Teach the biblical thought processes involved in temptation and sin, trust and obedience.
Pray for God's help in bringing them to repentance.
Remember that the goal is self-motivated recognition of wrong attitudes leading to self discipline.
Rather than arguing with them, simply ask them what they chose to do.
"Did you choose to obey Daddy/Mommy?"
"Was your behavior godly?"
"Were you practicing self control?"
"Were you in submission to your God-given authority?"
Exercise their consciences. Ask if they were obeying the verses that they have learned. Review these verses.
Express your disappointment over their choosing to follow Satan rather than following God.
Make sure they know you chasten them because you love them, that you love the sinner but hate the sin.
Each discipline session must be a significant event, one that motivates them toward a contrite heart and the joys of "the narrow way" (Matthew 7:13-14).
After chastening, work to restore loving fellowship by having them genuinely ask your forgiveness and God's (1 John 1:9).
NEVER, NEVER, NEVER chasten out of anger. "For the anger of man does not achieve the righteousness of God." (James 1:20) Bring your attitude under control first, so that you do not violate Ephesians 6:4: "And, fathers, do not provoke your children to anger..." Correction in anger begets more anger.
Never use sarcasm, ridicule, scorn, or humiliation.
Do not compare one child with another.
Do not make threats.
Do not argue with the child. Keep it simple: "Did you obey my words?" (Col 3:20)
Do not allow them to scream or jump around when you chasten them. This is further rebellion and shows a lack of repentance - no change in heart attitude.