I don't have any kids, but I have plenty of opinions, so here's my advice.
Firstly, I don't think 12 and under should be bothered with these big issues. So here would be my advice for teenagers:
1. Forget your social life, school is more important than you can imagine. If you screw up high school and college, you really could make the rest of your life suck very bad. This is no joke.
2. If you do screw up, you've set yourself back but it's not the end of the world. You can always start over, it just gets harder and more depressing the older you get.
3. Watch your credit like a hawk. Don't fall into the trap of overspending. Money is power in this world, and that's why good credit (and education for that matter) are so important.
4. Understand that we may have a monetary system collapse / Depression unfolding. If not now, this is very well inevitable within your lifetime. Social Security may not be there for you in your older years -- that seems a very distant time for you, I know, but trust me what you do now affects how happy or miserable you'll be in those golden years.
Also, peak oil is going to force you to live a different kind of life than what you do now. There are also mutating viruses out there, and a lot of your favorite foods are probably very bad for you to eat. And then there's climate change.
The point is, a lot of bad stuff is going to go down in your lifetime. Deal with it. This is your cross to bare. Your challenge is to find happiness, stability, and success in spite of what life will throw at you.
5. Don't let this Doom stuff scare you, or depress you. This is really too deep for a teenager to dwell on too much. The main thing to remember is to use this knowledge to put your life into perspective. It's OK to enjoy cool gadgets, clothes, whatnot.. just never allow your self esteem to get wrapped up in these material things. You want to be strong enough to survive and prosper if and when you lose all those things.
5. Be careful with your future romantic relationships. Nothing has the power to screw your life up more than the wrong kind of partner. Peak Oil hath no fury like a woman scorned, so they say.
6. Don't do recreational drugs. It's OK to never even try them, trust me you're not missing *anything*. Also be very wary of pharmaceutical drugs -- do the research, know the risks of any pill you take. You may think drugs are cool now, but if you fry your brain you'll be anything but cool.
7. Don't smoke cigarettes. Once you're hooked, it is incredibly dificult to stop. And even when you stop, you'll miss it the rest of your life, so don't even start.
8. You don't think it is, but driving a car is statistically one of the most dangerous activities you will do as an adult. That's why it's important to be a cautious driver. That's why it is critical to not drink alcohol and drive. Car wrecks are very scary, and no fun at all. So drive carefully.
Oh, and Merry Christmas.
