What you do when your young, effects how you will live when you are old. Feel free to quote me on that.
When I was a 20-year-old, I was invincible. I ate terrible, smoked, drank too much, and wasn't concerned with my education because I had a good job for a twenty-year-old. By the time I was 27, I realized that if I didn't make some changes, I either wouldn't see old age, or if I did, it wasn't going to be pretty. At least I realized it while I was still young enough to make the necessary corrections. Good for you to ask for advice to give you an advantage in life.
1) Take care of your body. It is the only one you have, and it must last a lifetime. Eating a healthy diet, drinking in moderation, and avoiding all tobacco products and illegal drugs are directly linked to your health conditions twenty, thirty, forty, and so on years in the future. Regular exercise has been proven to lead to a higher quality of life now and in later years.
2) Exercise your mind. The mind is a muscle. If you don't use it, you lose it. Read. Everyday. Reading is one of the best ways to keep the mind active as it activates almost all areas of the mind. Read a wide range of subjects. The wider it is, the better you will be able to make connections.
3) Write everyday. Whether it is in a journal, a letter to penpals, or answering questions on Quora, writing well takes practice. With email and text messaging becoming such a large part of the business world, people automatically draw assumptions about your education and intelligence based on how well you write. Poor spelling, sentence structure, and punctuation will close doors that you never knew existed.
4) Experience new things. If you can, travel. If not, read about other places or watch Youtube videos. Get to know that there is a bigger world out there. Learn about other cultures. Try new foods. You will be surprised at what you discover.
5) Invest in yourself. Education will open doors for you like you can never imagine. Statistically, better educated people are wealthier, healthier, and live longer lives than their less-educated counterparts. A few short years at a university will give you many advantages in life. Once you get your degree, never stop learning.
6) Plan for you future. If you can afford to, open a retirement account today even if you can only afford to put in $5 a month right now. Too many people wait until in their late 30s or 40s to start planning for retirement. The effects of compound interest on that extra decade or two can literally mean the difference of hundreds of thousands of dollars more that you will have for your retirement.
7) Create a close relationship with someone or several someones who are much older than you. The advice that they will give you and what they can teach you will help you avoid many of the mistakes that 20-year-olds make. These older people made the mistakes when they were your age. Why would you want to repeat them if you can help it? Save yourself the trouble and listen to them.
8) Think. Too many people know stuff, but they don't think about what they know. Learn to reason logically. You will solve many problems in life by doing this. When someone makes a statement, even if it is someone in authority (such as a doctor or scientist), weigh the evidence that they present. Never accept anything just because someone said it. After reviewing the evidence, you may agree with them, but that is because you can see the proof for their claim. If you don't agree with them, weigh the evidence you have to support your claim to make sure it is not faulty.
9) Learn empathy. If you can put yourself in someone else's shoes, you will become a great person. At least to one person. If you can see the other person's reason in an argument, you will be able to say the right thing to diffuse the situation.