These are some behavior modification techniques that might prove helpful:
1) Define clear expectations for your child and stick to your guns. There are basically 3 rules to follow. If they follow these rules, you will be happy and they will succeed in life. Those rules are:
a. SHOW RESPECT - be nice,
b. BE RESPONSIBLE - do what you are told,
c. TAKE RESPONSIBILITY - own up to your mistakes.
Write these rules down for your kids and make sure they understand what they mean. if they will follow them you will be happy and they will be successful!
2) Use effective communication:
a. Say what you mean,
b. mean what you say,
c. but dont be mean with what you say.
I know this sounds cliché, but it has been proven to be a very effective method of communication. Basically what I am saying is, first of all, be careful what you say. Make sure you are willing and able to follow through with any threats or predicted consequences. Secondly, if you say you are going to do it, be sure to do it. Last of all, if you follow the first two steps, there is no reason to raise your voice. Back up your words with your actions, not anger.
3) Be Consistent. Never give in to their demands or manipulations, no matter how tempting it might be. You are the parent and you must remain in control.
4) Expect compliance without warning, They will meet your expectation. if you count to 10, they will wait till ten. Teach them to respect you by complying the first time they are told
5) Use Natural Consequences as much as possible. If they wont put it away they lose it, etc. This may be inconvenient, but carried out, can be very effective.
6) Give as much affirmation and positive attention as possible. This can never be related to their negative behavior, but during those times when they are behaving. Make sure they know you notice.
7) Give each child some special mom and dad time. Try to schedule some special time between each child and parent on a regular basis. i am only talking a few minutes a day or an hour or so a week. This is totally unrelated to their behavior. It is not a reward nor can it be removed as a consequence. This is simply because you love that child no matter what he does. They need to know you care simply because you care.
I know this is a lot to swallow, but I really believe if you will apply the principles. you family life will be revolutionized. Give it a try!