Note: If you are reading this and you are not a Christian don't worry! You can still apply many of the ideas to your life. Also, getting to know the creator of the universe is strongly recommended!
Finish High-school and get married, before kids
Finishing High-school and getting married before you have children. This one piece of advice has shown to have better outcomes for families and for family finances.
Get Married to the Right Person
A lot of people get married to the wrong person or they don't get married at all. I recommend that you do get married and that you take marriage seriously enough to very selective about who you marry. Many of you will get the wrong idea from this statement. What I mean is waiting until you find someone who shares your values. This is crucial. Much more important than someone who is attractive or has similar interests.
Related Post: Marriage is Hard, Especially if you start one without being prepared!
School / Career
Do Not Go Broke for a Degree
Unless you are rich, I recommend you get a two year degree for reasonable amount of money. Then get a job so you can pay for a four year degree. Don't know what you want to get a degree in? Then you are not ready for college yet. Do not get a four year degree in some random thing just because the world says you are worthless unless you have a four year degree. (or Masters degree or PhD)
Education with Focus
Focus your education on finding something you are interested in AND that will pay the bills. If you have to pick one or the other, then pick paying the bills. You can always start a hobby or side business doing what you love. Paying your bills first may be the gateway to doing what you love. Where as the other approach of not paying your bills, does not normally let you do what you love.
Find a Job You Love
If you find a job you love, it will make going to work easier. Often people dream of this, but never make it happen. Often this starts with knowing what things interest you and that you are good at when you are young. Changing your major in school is worth the extra effort if it gives you a career you won't hate. You may have to get a job you hate until you can find a job you love, but do not settle. Keep searching.
Live Below Your Means
Spend less money than you make. This is hard. I have struggled with this, but it has great potential. The best time to apply this idea is if you get a pay raise, do not get a new house and new car immediately. Wait as long as possible before you increase your expenses.
Save money and Invest
If you do not spend all your income, then you will have some left over to save and invest. I wish I had started this earlier. Your financial future is more important than you realize when you are young. Save and invest early!
Debt has become vary normal to the American way of life. Do not be like everyone else. See debt as bad and dangerous. Pay for everything you can with real money, not debt. Debt can destroy you.
Read The Bible Daily
I read the bible daily, but I did not start doing it consistently until I was in my 30s. I wish I had started younger. A few minutes every morning with God in prayer and scripture really directs your mindset for the rest of the day.
Understand What You Believe and How to Defend It
I wish I had studied the Christian faith more deeply earlier in life. Understanding the reasons for believing something is true really helps with confidence and your desire to share. Christians should be on a quest to believe the most true things and the least false things as possible.
Know Who You Are
If your identity is in anything other than who you are as a follower of Jesus Christ, then you are in trouble when life gets shaken and everything is turned upside down.
Listen and Seek to Understand more Than you Speak
Listen more than you speak. Learn about other cultures and other perspectives. Do not speak into something until you have first learned much about it. After you become an expert on a topic, continue to approach people with less knowledge in humility.