Model for your teen the fact that most of us can't buy whatever we want when we want it. We have to plan and save to get the things we want. Then help them make their own plan of action. Encourage your teen to make a plan for buying things they want. . . to save for the new stereo instead of looking for instant gratification or easy credit. Make a chart showing how saving a little money every week or every month can help achieve a particular goal in a given amount of time.
Help plan a job-hunting campaign.
When your teen has to work for their money, they may appreciate it more. If your child is an early teen, a paper route may be a good option. Start out with the take home pay and help find ways to stretch it to cover necessities, fun and savings for major goals. The Parenting Resource Center on the Web.