Summing up what our scripters have posted into a single sentence would be a hard task. But if there is one point that would fit the criteria, then it would be that
experience is the best teacher.
While it is good to learn from others, you must also do some learning on your own. As everyone is posting stories of their experience in programming, I thought I'd heap some on the bandwagon too.
I do not have much experience in the area of using different programming languages, as our teachers in high school were (sad to say) less than optimal when it comes to computers. However, as I mentioned earlier, I did some learning on my own. While others were busy carrying out the simple codes the teacher gave for simple laboratory exercises, I dabbled with the functions, screwed around, and made a little "for fun" programs of my own. Ironically, these programs I made as a result of fucking around during computer class had more intricate codes than any of the lab exercises given.
Not a very good strategy if you wanted to maintain optimum academics, but needless to say, it provided a better learning experience for me than the rest of my batch, which was rewarded when I was given an award for best in programming during my High School graduation.

Now that I am studying more languages after taking up Computer Science in a certain premier state university, I still enjoy the same quick learning as I had in High School for every new function I come across. Learning is a process that never ends, especially in your younger years, so make the most out of it.
Pieces of advise to sum it up:
- Experience is the best teacher.
- Learning from others is good, but do some of your own.
- Never try to master a topic until you have mastered the previous one.
- Set good standards for yourself and try to reach (or exceed!) those.
- Enjoy what you do.
I've done well with those five. You may have a different set of principles in learning (which I believe has a relative nature to it as well), but the same underlying concepts remain.
Good luck in your future endeavors.