Always double-check.
For example, the community you are posting in.

Everybody else is just faking it, too.

Don't drink and smoke.

Don't put your dick in crazy

Learn to shop, cook and eat without highly procesed foods

Clean the toilet when you are done

Use sunscreen.

Buy a plunger BEFORE you need one

Don't do drugs. But if you're going to do drugs avoid anything you have to inject with needles. There are plenty of fun things you can smoke, eat or snort.

Don't take advice from people on the internet.

Upload posts to appropriate communities.

Strengthen your core. Lower back pain in your mid-30s is a bitch. Also, take care of your teeth and floss everyday. Start investing early. Any amount you can set aside, no matter how small, will payoff if you start early.

Live below your means.

Let go of any fear of others expectations for you as soon as you can. Explore what interests you and don’t let others stop you. People come and go, but they’ll come to you faster than they leave if you’re a confident and passionate person. You can only be that if you work on figuring out how you want to live and chase that life.

The biggest advice I can give you is, you need to try to be social. It's easy to hang out with friends in high school because everyone's locked into the same building every weekday for 6 hours.

Once you're an adult, you no longer have that limitation. Even college is more of a "go to class for 2 hours a day then leave afterwards" type of experience. It's certainly liberating to not be forced to be someplace for long periods of time, but it also means that the primary reason that you hang out with your friends (ie, because they're already there with you) is now gone. It can make for a very lonely experience.

You need to go out of your way and actively maintain your friendships. Make plans to meet up at least once a week or something. Otherwise, you won't really get another chance to make deep friendships

Travel if you can afford to, it’s an incredible way to learn about the world and meet different kinds of people. Look after your teeth.

Stay away from gambling sites. If you’ve got extra money and want to watch it grow, invest in Exchange Traded Funds (ETFs) with a low/no fee trading account. Stay away from meme stocks as well.

If you do invest, diversify your portfolio. SPY is very exciting but it’s heavily tied up in the AI bubble. Try to more international markets, clean energy, minerals, heavy industry. No matter what happens to the AI companies, we still need energy and resources to build stuff and keep our economy going.

Read about taxable and non taxable trading accounts in your country. Try to use those to avoid having your savings eroded by taxes. You will pay plenty of taxes on your income, so don’t worry about that!

Learn how to clean properly, stains especially.

Practice a few basic but yummy recipes (trial and error for which work for you) and get good at cooking them.

Remember everybody is living their own life at their own pace. Don't feel like you aren't doing it right.

Ask for help when you need it. Nobody can do it all alone.

Stay in contact with friends and cut ties with people that make your life worse.

Don't stop training, don't eat shitty food (at least, not daily), don't believe anything you hear or read and always double check it.

USE A CONDOM!

Do the things. Do them. Don't leave them until later. There are always things. If you don't do the now things, thinking you can do them later, there will be other things later.

Not doing the things only puts you behind, possibly forever.

Do the things.

If you haven't yet, question what being a man means to you, and what being a good person means to you.

You will, throughout your life, find those definitions challenged. How you respond to the first will help you to develop a stronger sense of how you relate to your gender, and how it effects the way you interact with yourself and the world. How you respond to the second determines your character, which is how the world will see you as a person, and with sufficient introspection how you will see yourself.

Keep growing. Keep learning.

Get to know yourself. What kind of person you are, what do you like, need and so on. Accept yourself as you are.

Sure, you can change your weight, learn new skills, become better at stuff and get stronger. I’m not talking about those things. Some traits just are the way they are, and fighting against them will only result in frustration, stress and sadness. Try to figure out which parts of you can be changed and which ones can’t. Treat them accordingly.

get a dishwasher, always read contracts, be confident during interviews, hydrate your skin, do regular exercise

Take care of your body is the only one you have, use sunscreen.

Spend time with your parents and people you love they are not going to be around forever, do things they like.

You have time, don't rush into things. Don't think you are 25 you should have a family by now, life is not a race each person reach goals differently and not all have the same goals. Search what makes you happy and do it.

Worry only for what you control, if you can control it you can fix it, resolve it so look for solutions but don't worry about what is out of your control, you won't be able to fix it you have to accept some things are they are and learn to life with them being that way.

Vote!

Local, state, Fed.

If you don't vote, you have no rights to complain about how government is functioning.

Start building credit if you’re in the US, but don’t treat your credit card like free money.

Don’t let yourself get addicted to alcohol (or any other drug).

Spend a decade commuting by bike if you can (rain or shine).

Get radicalized by the terrorists (people who just wanna have a nice safe society free of bigotry and hate).

Do not discard advice from older people because you think "the world has changed" and old people are out of touch.

ALL the advice that the older people in my life gave me in my teens about money/college/jobs/people/relationships was right, but I refused to listen to any of it because they were old and didn't understand my life.

Don't force yourself to learn every life lesson the hard way, like I did.

You'll probably learn everything the hard way...but I tried to tell you.

Lots of good advice here and I am not THAT old but here are a few things I wish I had realized sooner in life (in no particular order or theme):

• No one really knows what they are doing, more experienced people usually have just made the mistakes already.
• There is a difference between being correct and getting someone to agree you are correct, the former is the most important and the latter is not always possible or desired and when to argue and when to let someone be wrong is a skill that takes practice.
• The less time spent worrying about what other people think of you the happier you will be and the easier life will feel. In almost all situations you spend more time thinking about whatever it is than the other person does.
• Always strive to be a good and like-able person but always remember that it’s impossible to be liked by everyone, sometimes people just won’t like you and that is okay.
• One friend you can count on is more valuable than 100 acquaintances, guard and nurture your valued friendships like your life depends on it because it might some day.

The biggest thing though, there isn’t one correct way to live your life and anyone telling you differently is probably selling you something. Always try to learn something from every situation and you will be fine, mistakes are a part of life. Anyway, hope at least some of that is helpful!

Buy quality things that will last a long time.

Paraphrasing Terry Pratchett, the man who buys a good pair of boots will have dry feet for ten years, and the man who buys a pair of cheap shoes every year will spend more and still have wet feet.

Go to therapy if you struggle with mental health - the sooner, the better. Change gets harder the older you get.