As a high school teacher, let me share what I feel the most important skills a young adult needs:
1. Be trainable- A wise man knows he knows nothing. Have enough humility to acknowledge that you don't know everything and then set out to learn as much as you can from everyone you can in your career field or interest.
2. Be consistent- Do what you say you're going to do when you say you're going to do it. Let all your work be your best work and accept nothing less.
3. Become a life-long learner- This ties in with #1 but warrants its own section. Successful people are always learning new things and many of them are ravenous readers. There is a correlation between success and learning so act now!
4. Be honest - Seriously, honesty is a forgotten virtue. When you lie you are labeled a liar, liars can't be trusted, you won't be promoted if you can't be trusted, people won't befriend someone they can't trust. It's really that simple.
You can take these four guidelines just about anywhere and be pretty successful with them. Unfortunately, these aren't really taught in public schools any longer, which is a shame because it's useful knowledge.
Edit: I came across this tonight. I think it's relevant:
Link