They say youth is wasted on the young. As I get older, I start to agree with the wisdom of that saying.
My baby daughter is barely 2 weeks old, but I have some advice that hopefully I can keep in my mind to give her that hopefully she will be able to find useful.
#1 We don't know what we don't know.
The problem for kids, starting in teens and going on through their 20s is that they don't know what they don't know. That's obvious. What's not obvious is that htey often don't realize that they are making decisions based on a lack of knowledge. Accept that knowledge isn't the same as intelligence and that sometimes understanding simply takes time.
#2 Don't make life-altering decisions hastily.
This sounds obvious but to get more specific -- many of the decisions that we have to live with on a day to day basis for the rest of our lives are made between the ages of 18 and 25. But we are scarcely equipped to make decisions that are going to have to be dealt with for the rest of our lives. Take care to recognize how decisions will affect the rest of your life. This is particularly true of relationships.
#3 Don't take the path of least resistance.
This is the #1 thing that I have observed that leads to long-term sorrow. Doing something because it is easiest. Many of life's choices aren't made, people just fall into them. The success I've had in life can be entirely put towards not taking the path of least resistance. In my case, I was driven by wanting to have some control over my life. But many people often end up in dead end jobs or unsatisfactory relationships because there wasn't a compelling reason not to get out of them.
#4 Decide what makes you happy and don't compromise on that.
There isn't a good reason to compromise on things that make you happy. If something makes you happy and it is not doing you any long-term harm and isn't hurting others, consider pursuing it.
#5 Don't let others determine how you view yourself.
It's amazing how people end up falling into choices simply because it is "whast is expected". As soon as you give other people control over how you view yourself you cede your own self-esteem and choices to the whims of others.