Start a yearly “review” right before school year. Raise allowance as appropriate. If they want more money, they’ll have to take on more responsibilities.
IMPORTANT: If you borrow money from someone pay it back as soon as possible. In full. If you borrow an item, return it in excellent condition. I’d say if you borrow a car, return it with a full tank of gas but hopefully by the time you’re driving there won’t be any combustible engines. So return it fully charged!
Set up automatic payments so they are initiated on your end, so that you send out money to the bill/ company you’re paying instead of giving them access to take money out of your account.
"Watch the pennies and the dollars will take care of themselves." - Ben Franklin
This works with money and with other areas: Be faithful in the little things and the bigger things will take care of themselves. For example, if you don't get comfortable with telling little lies then you'll never tell big lies.
It’s fine, great, to be thrifty. But please don’t be cheap. Hard-earned money should neither be squandered or hoarded. Enjoy your success! But save more than you’re comfortable with. It’s like my running coach used to say: Keep going until you feel like you’re gonna poop your pants, then push yourself to do another mile. Point is, it should hurt a little.
Have a yearly “review” right before school year. Raise allowance as appropriate. If they want more money, they’ll have to take on more responsibilities.