Telling them why they should do something is more effective than telling them outright what they should do. The latter will sometimes antagonize them or will cause them to rebel as they feel that you are ordering them about without any reason. Kids, as you well know, do not want to be bossed about.
2. Give them piggy banks.
Having coin banks may seem outdated in this digital age but it is nevertheless still effective in teaching kids how to save up. Tell them that saving up will allow them to have some money should they need to buy something that they want. A portion of their lunch money, for instance a quarter or two, is a good way to start.
Of course, do not discourage them to buy food when they need to eat but tell them though that if they are not hungry, they can save the money so that they can use more for the next day.
3. Get what they need
Controlling what they put on their plates during dinner will help control the urge to get more than they can use. Ask them to clean their plates every time. That way, they will only get the food that they will be able to eat. This will teach them about saving and buying only the things that they need. This is a great training in the future so that they will not grow up with maxed out credit cards, buying things that they do not really need in the first place.
4. Being a role model
Face it. Whatever your child does is only a reflection of what you yourself are doing at home. So if you want the kids to start saving up, make sure that you are also doing your part in saving in this times of economic recession.