Don't expect the school to do all the work , as a parent you must work outside of the walls of the school. Help your child with tutoring or get a tutor if you can't do the work. Keep your child out of the clouds of television, internet, phone, texting, music that does not stimulate the mind, and yes don't give them enought rope to hang themselves. Children need guidance regardless to how tall or big they are.
Find out what your child's talents are and cultivate them. Keep them active in activities that will be a growth for their future plans. Know what they plan to study in college regardless to how many times it changes and help them narrow the list so they can focus on one or two areas.
Spend family time with your child and be a good listener so they do not have to search the school halls for answers. You should be your childs best friend. A best friend is there in the good and bad times. Trust and open conversation will go a long way. You do not need to spend a l of money to help your child there are hundreds of resoures out there, research and get your child the necessaray tools they need to succeed.