Preparing for a piano exam is not for the faint of heart. Here are my observations from years of teaching and examining.
1. The student has to like the music.
2. Parental supervision and encouragement is required. Child prodigies do not practice alone. So it is unrealistic to expect the normal piano students to practice alone and be successful.
3. Sufficient practice time has to be arranged. Early grades require 30 minutes a day, middle grades up to an hour, upper grades more than an hour, associate level two to three hours a day. (I practiced and studied for 5000 hours to earn my Grade 10 and ARCT over four years. No kidding.)
4. Every short cut the student takes diminishes the outcome.
5. Last advice: Don't sign up until your music is memorized.
Last note: The completion of my Grade 10 was the most difficult thing I ever did as an adult and as a musician. Berklee of Music was a walk in the park in comparison. But, it was the most rewarding and exciting thing I ever did too.
You've got to learn your instrument. Then, you practice, practice, practice. And then, when you finally get up there on the bandstand, forget all that and just wail.
I'm a professional pianist and music educator in West Toronto Ontario. I'm also a devoted percussionist and drum teacher.