Also, a big area is financial. You'd like to avoid loading your youth up with college debt, however, you shouldn't be mortgaging your future to get them through. Start having them save for a college fund and also pursuit scholarships. You should know what you can afford and what you are planning to contribute and make sure they are aware during high school so it can reinforce the importance of their good grades and additional efforts that will help them get scholarships.
Most importantly is their decision making process. It develops the whole time they are growing up. Help them to become independent and develop the ability to be on their own. They need to learn responsibility and the value of money. When they enter college, put them on a budget. Let them manage to that budget without bailing them out all the time. Blowing a budget is something they need to learn. 10% miss is much better than a 100% miss. They need to develop that discipline of spending only what they can afford. Too many families and kids are saddling up with too much debt thinking when they make it big time they can pay it all off. Think about avoiding all the debt and getting through college with minimal debt.
Regarding major... don't switch when it extends the graduation date. Too often youth switch and add another couple of semesters. That might help the college revenue stream, but rarely does the cost justification exist. Few undergrad majors are going to get you through life. You will need to learn a lot more in your first job. Graduating with a bachelors degree teaches you to learn and adapt. It says that you have dedication and you know how to complete things. The goal should be graduating within 4 years with your bachelors degree. Get through it as quickly as you can, learn as much as you can and then go get some career experience and prepare to get a Masters degree! Also good to have internships between semesters. Even if they are without pay--the experience is what you need--beyond working at a fast food restaurant (unless you are planning to work in that industry).