The first thing is to get some mason jars (or other similar container), and write the verse Philippians 2:4 (Do everything without whining, arguing or complaining)..Also, write the child's name on it.
Second, cut up little pieces of paper, I would cut about 40. Each piece of paper represents money. For my kids each piece was worth 10 cents.
Last, fill up the jar with the pieces of paper, close the lid and set it somewhere within view of your child. Tell them they have $4.00 worth of cards in the jar, and in one week we will tally up the cards, and see how much they have to spend. (I chose the Target dollar spot to take mine).
Tell them every time they whine argue or complain, they are loosing one of their tabs, and do it. I repeated the Bible verse each time they lost a tab. I really liked this, and found it very effective for my children. Especially my almost 7 year old.
That's it, have fun, and enjoy those Happy Kids!!