I just had a 17-year-old Less Wronger e-mail me for advice regarding the Thiel Fellowship after reading my application essay from last year when I was 19. We had a long instant message conversation where I gave him a lot of advice which he seemed to find highly useful (my biggest piece of advice was to start teaching himself programming using Learn Python the Hard Way, shamelessly asking for help using a pseudonym on IRC channels, forums, and Stack Overflow if he got stuck).
It seems likely that there are other Less Wrong users who still live with their parents who could benefit from life and career advice. I'm especially interested in reaching those who see reducing existential risk as a major life goal.
A related idea is for people who have some goal they want to achieve, like having a romantic relationship with someone of their preferred gender or being admitted to a prestigious graduate school, to pair up with someone who has accomplished that goal.
So if you're a young person who would like advice, an older person who would like to give advice, a person who wants to accomplish a goal, or a person who has accomplished a goal and is willing to help others accomplish that goal, consider leaving a comment on this post so you can find your counterpart.
I realize this post is a bit open ended--consider it an experiment in tapping Less Wrong's social capital in a novel fashion.
Very few people know what career they want when they're seventeen. Of those people, a significant proportion end up either doing a different job or displeased by their choice.
This is what I did; it may or may not work for you. Go to a college with a wide variety of class choices and highlight everything in the course book that looks interesting and that you have the prereqs for. Narrow it down to four or five classes by eliminating courses that occur in the same time block as another course you're more interested in, courses with dull or unintelligent teachers, or courses that come from disciplines you've already taken a lot of classes in. (Note: if you have general course requirements, take those courses.) That should give you some data to eliminate majors you're absolutely not interested in; for the rest, assuming you have not gotten an all-consuming obsession with one particular field, look at the BLS statistics to see which one has the best overall job outcomes (income, hours worked, unemployment risk, etc) and major in that one.
General warnings: unlike most people here, I am not a STEM major; my experience applies strictly to the social sciences and the humanities. I also have not attempted to get a job in this economy, so take my advice with a grain of salt.
Related idea: look through the course catalog for the course prerequisite chains that are the longest (they will probably be for math, chemistry, and physics). Take the 1st course in each of the longest chains early on in your college career so you'll know right away if one of the long-chain majors is for you (as opposed to a few years later, when it will be too late to make the switch).