I am starting a practice tips list here today and will add to it as we develop the project here at the Tale Teller Club.
1. If you can play one note well you can play a whole piece well. Practice single notes a lot, then pairs, shifts, etc. These are the building blocks, don't miss any out or skirt around details.
2. Repetition makes perfect. Muscle memory is a great aid to performance and setting habits into the subconscious will help you greatly. Muscle memory often remains with you all your life.
3. Practice slowly, even when you are really good. Slow playing helps you hear mistakes.
4. Record yourself often. You can hear your mistakes better on a recording than live.
5. Use a mirror if you are a string player. Mirrors can also help with stage fright as you get used to seeing another person in the room.
6. Leave your instrument in an easily accessible state so you don't put off getting it ready.
7. Look out of a window or at a painting as you practice.
8. Sight read 20 minutes a day.
9. Always push above your weight.
10. Study music first, understand key changes and spot the hard bits.
11. Listen to your music by an expert, over and over again.
12. Mime to a performance.