No matter what you teach your children, they are going to make their own mistakes, however, you can still teach some good habits when they are young which they will carry with them throughout life.
At birth you can set up a savings account for your child so as they approach toddlerhood you can explain that they have pocket money each week that goes to the bank to “grow more money”. As they get older you can explain that perhaps if there is a toy they really want they can take it out of their hard earned savings but explain that this will mean they will have less money to buy something else in the near future. This will instill a sense of thinking before buying.
Children should also learn that money is not something that just gets given to them. Pocket money could be rated against how well the child is doing at school or in chores and bonuses given for any outstanding achievement or good behaviour. They money should always go to the bank and withdrawn for those special items discussed before.
When your children are teenagers it will become more difficult to control what they are spending, but the lesson should continue that good and responsible behaviour yields rewards and this should now include how they handle their money. If yu see your child putting money away each week and spending wisely then perhaps it would be safe to increase the allowance, but conversely if your teen asks for a raise in their allowance because they are squandering it perhaps it would be better to keep the allowance the same.
Offer your advice as your child gets to university age about different accounts and borrowing facilities but be prepared to be ignored. Your child may well make mistakes but eventually they will remember all that you taught them.