The famous American ADHD expert Russel Barkley emphasizes the need for immediate positive consequences in the behaviour modification of ADHD children.

• Use more immediate consequences
• Use a greater frequency of consequences
• Employ more salient consequences
• Start incentives before punishments
• Strive for consistency
• Plan for problem situations and transitions
• Keep a disability perspective
• Practice forgiveness

This is very hard to achieve - especially if one or both parents are also affected by ADHD.