My son just turned 20. Here is what I have learned.
My son has just turned 20 and so we have aged out of this group. Here is what I have learned through the teen years.
No teen is all good or all bad (though my son was more toward the bad end of the spectrum). Get to know your kids' friends (especially if they are bad). That way, when you are looking for your kid at one in the morning they will tell you where he is.
Don't let school suck the creativity out of your kid. In the real world we are not asked to sit for hours writing an exam. We are allowed to ask for help, look things up and work as a team.
Sometimes kids need help finding their way. Teach them how to job search, help them write their resumes and take them to places you know may hire them.
Don't be in a rush for them to find their life long career in high school. It's not the end of the world if they don't graduate on time either. Encourage them to try different things, you may be surprised at where they end up and what they are good at and enjoy. If they are not "academics" they are still valuable human beings.
Keep in mind that they are sneaky...if you think it's their friend john texting them be aware it may be their friend kate (they are the ones who have put names to the numbers in their phones) . Also, if you think you have all of their passwords for facebook remember they can open another facebook account under a pseudonym.
And lastly, this too shall pass. Just stick by them, support them, and know that at the other end is an adult that went through a lot of crap as a teen and you couldn't be more proud of the person they have become.