Thank you for the question. The older I get, the more unqualified I feel to give advice. I urge anyone reading this to take it with a grain of salt, as these are personalized to me, although of course I am writing with the hope that you may find it generally applicable.
When I was 16, it was 1998. Now, aside from the easy stuff of telling my past self to buy and dump all tech stocks as a sector by 2000, then pour the proceeds into commodities and real estate with an exit date of 2006, while sitting on massive long-term bond positions for at least the next 15 years, the real stuff has to take into account that when I was 16 I was in high school, in year 10 of a 12 year sentence in the public school system, and that is the defining precursor:
1. Unlike in high school, real life doesn't have a 'track'. There are no milestones or markers at the end of semesters, years, video game-like progressions that tell you what a good job you're doing. The grading system invites the mindset that your success is to be judged on a relative, rather than absolute basis.
2. On a related note, it always helps to have an understanding of the dynamics of any future situation you are entering, but especially when you're entering a very highly competitive game. Admissions rates at highly competitive schools are between 5-10%, depending on surges of demand due to factors like recessions or demographic trends, offer rates at highly competitive firms can be as low as 1-2%, success rates of startups probably around the same low single digits, probability of becoming a pro athlete in any major US sport (except baseball) is around 1% even if you are a NCAA athlete, and so on. So basically, your expected outcome is to lose.
When you take a view of things like this, hopefully it becomes more like a game to be played – which it is – and less of a life-or-death situation where there are only binary outcomes, to either win or lose. ‘Losing’ at games like this (which Peter Thiel calls tournaments/gauntlets) are not verdicts on your value or worth. Move on and play another one. Accepting this viewpoint will help your mental health.
3. Fear and insecurity may cause you to choose the paths that everyone else is taking. This is called following the herd, and that is never a good reason to use in making any future life decisions!
4. It may comfort you to know that the popular/cool kids do not seem to stay that way for very many years after graduation. If you are one of them, though, let it be a reminder to start preparing for a second act. Change is the only constant.
5. When you're a teenager, you act up because you want the attention, but at the same time, you are very insecure about how you are perceived. It may either cheer or depress you to know that the prevailing sentiment in life after high school is indifference, in that no one cares about you, the way you look or dress, about your dreams or lack thereof, about whether you are doing well financially, etc., beyond a surface level. The world doesn't owe you success, it doesn't even know you. Think about that for a moment. And it doesn't care. So make us care.
6. Another point about image and being self-conscious. People in general do not actually don't see you the way you see yourself, or want to see yourself. A good friend is someone who will point out how people actually see you.
7. Unlike when I was in high school, it is commonly understood now that the brain is endlessly plastic, that neurons can grow and regenerate. Don't put static labels on your skills or abilities, by saying you're either 'good' or 'bad' at them. You will quickly become outdated if you don't continue learning, and you can always, always re-create yourself mentally and physically. While setting aside 4 years to accomplish or learn something seems like a prison sentence when you're 16 (understandably, because it's 25% of your life), just know that it usually takes that long before you can really do anything of consequence in the real world. People who look like overnight successes usually have a trail of blood, sweat, tears, and luck behind them.
8. On that note, always try to cultivate that which is unique about yourself.
9. 'Doing your homework' means something different when you're older. You'll be surprised at the sheer amount of ignorance and competence that exists in the world, not because people don't know what to do, but because they are too lazy or arrogant to do it.
As an extension of this, it is really easy – in both college and beyond – to achieve the equivalent of a B (Pareto Principle). This is the 80% complete, sufficiency level. But how I interpret the principle is that sometimes it is easy to set yourself apart from the herd just by using things/materials that are already, just there. This recalls Mark Cuban's RTFM (read the frickin’ manual) strategy (read Part 2 of this: SharkTank & Success & Motivation) which he used to achieve his first small successes. I've used this principle in building a few businesses.
10. While the closed nature of high school society enforces punishment on people who cheat, steal, and mislead others, in real life there are less constraints. You will almost certainly encounter deceit in all forms, many of which you have never imagined. Be skeptical of people who have no skin in the game, in any field, whether they are people trying to teach you or take your money. You would think that it is easy to identify get-rich-quick schemes, but it is not. Your emotions get in the way. If someone does come to you with some kind of investment, consider for a moment that even the greatest VCs hit in the low single digits, that Warren Buffet probably sees hundreds of pitches a year and may only swing at one or two, and ask yourself what your probability of winning is, and if you can afford to lose 100% of your money. Don’t let greed get in the way.
11. The world is not fair. In fact, every society that has tried to create an equal society has always created even more inequality. The only thing that is fair is that time passes at the same rate for everyone.
12. Don't let the combination of #5, #10, and #11 make you cynical, because the world is truly larger and more beautiful and profound than you can even imagine, perhaps than you will ever know. Life post-high school is kind of like entering the Total Perspective Vortex (Total Perspective Vortex) , with less belittlement, and more awe-inspiring features built into it. You will be surprised everyday. Continue cultivating a sense of wonder and curiosity.
13. It's not 'cool' to be cynical. You do this when you're younger to avoid disappointment, so you make fun of people who try. Ask anyone over the age of 20 – slackers aren't cool. The world belongs to those who hustle.
14. So…don't make the mistake of thinking that because it doesn't exist, it's impossible. Think about everything in the world that exists today, and think about whether it ever…didn't exist.
15. In relationships, when people don't invest in you to the same extent you invest in them, I'd call that an unfair trade. Or even a swindle. Try to move on.
16. You will end up with the one you deserve. No one is going to 'see' the real 'you', be attracted to all sorts of unknown attributes that you didn't communicate, and be the perfect person for you. Even the best relationships require some work. But when it’s bad, have the courage to walk away. And when it’s good, have the courage to stay.
17. At your age, the cost of picking up all sorts of options in the form of skills, experiences, contacts, etc., is low, almost free. This is a combination of your minds working like vacuum hoses and you surging with insane levels of energy (these are your advantages), and your lower opportunity costs (unless you've started a huge enterprise or have family to take care of). This is the reason why people older than you fall behind in technologies, why some older people don't have the time to go back to school, why they stagnate at the level of their incompetence (see Peter Principle ). When you’re young, pick up these options. Sample and experiment. Having options like this + serendipity will result in all sorts of outcomes you can’t imagine now. I’m reminded of Steve Jobs’ commencement speech when he said the Mac wouldn’t have had beautiful fonts if he hadn’t dropped in on a calligraphy class…
18. Exponential growth is something that people have a hard time understanding. But as a thought experiment, consider that if you got even 1% better every day, you'd be 2x better in about 8 weeks.
19. Appearances at your age will change dramatically so don’t be so insecure about them. The same droopy eyes the guys made fun of as a kid will be sultry ones that will break their hearts later. That skinny boy in the corner will fill in. Baby fat melts away. Jawlines become defined. You start becoming more comfortable in your bodies, in your voice, and that single change of greater confidence and assurance, more than anything, enhances your attractiveness.
20. You can't wait for certainty. Don't hold yourself to that standard, and don't be afraid to make mistakes. Life decisions are by definition ones that have no clear answer. Once you start making these decisions, and start tasting the consequences of your choices, congratulations, you have experienced adulthood.
But when you are completely, absolutely stuck, with two options about dead-even, I would advocate using the strategy written about by Nassim Taleb in Antifragile for the Buridan’s ass ‘paradox’ (Buridan's ass) – just choose a random direction and swiftly kick the donkey (in this case, you) in that direction. Waiting is also always an option, but I'm assuming that you have eliminated that one.
21. A long time ago I read a quote by an athlete saying that as a kid, he had a vision of the type of person he wanted to be – and although he didn't know exactly how, by kind of always holding that vision in his mind, he had slowly become the man he wanted to be. I am finding this to be true. When you ride a motorcycle, you look left, you go left. Tony Robbins puts it another way: where focus goes, energy flows:
https://www.youtube.com/watch?v=WpKltuQd0qQAnd that energy is the building block of creation. Don’t waste it.
22. I had the most vivid dream a month ago, which was the impetus for me to start writing an answer to this question. It was a dream about the house I had grown up in, when I was 16. There was my mom when she was young, when she had the energy of a much younger woman, there was my dad, when he had much fewer gray hairs, less wrinkles, with a bounce in his step, with the energy of a much younger man, and there was my sister, when she was still my kid sister, running around. It was one of many points in time when I had been looking so hungrily ahead, dreaming of how great the future was going to be, that I failed to realize how really perfect that moment was too. And that moment will never come around again.
So enjoy the journey. As Cervantes said, the journey is better than the inn (a quote by Miguel de Cervantes Saavedra).
Hope this helps!