I wish I had been told the following:
1. Consistency is the key: you will get far more results from doing ten minutes daily never missing a day, than by doing 5 hours a day irregularly.
2. Mindless practice is useless, no matter how much effort you put into it. I truly wish I had access to Bernhard’s posts on practising technology when I was a teenager.
3. Only play what you love, pieces that you would like to have in your repertory. These pieces will open all doors, if you don’t look at them as some key pressing activity, but regard them in their totality (movements, theory, musical history etc.). Never waste time on stuff you have no interest in, but which you think may have some benefit. Whatever is of benefit to you will naturally grow from the things you like.
4. Don’t follow blindly what a teacher says. Rather take it as a starting point to your own investigations. Then come back to the teacher and question him/her (in the spirit of discussion rather than argument, searching for light rather than for heat).
5. Pay no attention to your emotional reactions – some days you will feel elated from your playing, some days you will feel depressed – Just keep practising/working. Learn to completely disregard such shallow feelings, they always come from a part of you that is utterly false.
6. Always have initiative. It is your job to decide the pieces you want to play. It is not your teacher’s job to do so. His/her job is to give you the resources to get where you want to go. If you have no initiative, you will end up following other people’s initiatives.
7. Pay the utmost attention to that inner part of you that tells you what is right or wrong, and always take a firm stand on what is right. Don’t sell yourself to anyone or to any system of thoughts/beliefs. If you feel uneasy about any of your actions (e.g most Bush voters) don’t do it. This feeling of uneasiness is all you need to know that you should not do it.
8. Decide on your priorities and then be ruthless in your social life: get rid of anyone who does not further your priorities, surround yourself with people that do.
9. Use fear as an advisor, not as a block. Listen to what your fear has to tell you, and then do it. And remember that a much better (in fact, the best) adviser is death. Always ask the three questions:
a. What would I do if I knew I was going to die tomorrow?
b. What would I do if I knew I was going to die in six months?
c. What would I do if I knew I was going to die in five years time?
This will clarify your short term plans, your middle term plans and your long term plans.
10. Tell him/her you like him/her. Usually people fear rejection, but the truth is, even if someone is not interested in you, the simple fact that you are interested in them is a powerful aphrodisiac.
Finally: Time is your most valuable asset. (Also understand that the advice above is what I would have told myself. For other people other advice may have been more appropriate).
Tip of the iceberg.

Best wishes,
Bernhard.