My boys are earning money every week through doing jobs rather than just getting an allowance. They are learning not only the importance of work, but also the importance of how to handle their money. For the most part, it works. Some days, they are naturally more lazy, but they quickly get motivated again the next day when I remind them of their goal. We learned this plan largely from Dave Ramsey - though we modified it a bit to suit our family dynamic.
OK, here's how it works. Pick 5 jobs for your child to do each day. Each job has a potential value of 10 points. If they do the job exceptionally well and efficiently with no whining, they get 10 points for that job. If the job is done satisfactory, but they whined about doing it, they might only get 5 points. If they didn't do a good job and they complained about it, but they got it done eventually, you might only want to give your child 1 point. Much of the point value for each job is up to your descretion. As they get older, you might want to make the jobs more difficult. Start them easy - at age 5 - and then increase the difficulty every 1 or 2 years.
When your child has finished his or her jobs for the day, tally the points at the bottom of that day. Do this each day for 5 or 6 days (Mon - Sat) depending on your schedule. At the end of the week you get to do PAY DAY. On Pay Day, you tally the points for the week. It's up to you how you want to break out the points. I suggest something like this:
10 points is worth $1.00. Then, count up by 5 points from there. For example, if they earn 47 points for the week, they earn $4.50. Does that make sense? I don't recommend breaking it down any further than that or else it will be too complicated with nickels and dimes. Keep it to dollar bills and quarters.
VERY IMPORTANT: Ask your child to set a goal as to what they are going to do with their money. They have a savings goal and a giving goal. They give about 10% each week to good causes - whether it be a non-profit, ministry or church. My boys have a goal to save $60 each by the end of March. They are each saving for a new Wii Game. Kaden is getting even more aggressive - he says he's already saving for a car - he has 9 more years before he starts driving, but hey, who am I to argue!?
Hope it works well for you!