First of all you should know the reading level of your kid. If he/she is a teenager then you can formulate a contract otherwise picture chart or token system will do the job.
Determine what you want to change in your kid and then set basic goals for your child. Make a list of the behaviours and assign easy tasks in the beginning. Again, the nature of task depends on their age. You can ask young ones to share their toys and if your kids are in teen age then you can give them something practical and challenging to do.
Remember, encouragement always push them to put their best. Appreciate them even on small achievements and give them rewards for showing improvement. You may ask your kid what he/she wants in reward. This will make the reward really meaningful. You do not need to buy expensive gifts; even a small token of appreciation can do the trick.
Make them realise that good behaviour will fetch admiration and love for them. Encourage them by mentioning their achievements in front of other family members. Giving rewards without any delay can keep them motivated and you will see a significant change in their behaviour.
You should make sure that behaviour modification plan is simple to follow and easy to administrate. If the given task is difficult and they are unable to succeed then there is probability that they will lose interest in this behaviour modification plan. That is why, it’s important to design a simple behaviour plan.
You must be consistent and patient enough to see the favourable results. Do not expect them to change overnight. It will take time so wait and watch.
Evaluate your kids’ performance at the end of day. If there is any sign of improvement, do appreciate the child.