1. Leaps and jumps
The piano can be a very difficult instrument to master. Getting a sound out of the piano requires no special training at all, unlike the rest of the orchestra. Getting a good tone out of a horn or a violin requires training and a music teacher. The piano is a hammered instrument so all you have to do in order to get a sound is press one of the keys.
I find that some of the most difficult aspects and techniques of playing the piano are playing in large leaps and jumps. The keys stretch so far in both directions, this makes hitting the right key so difficult.
2. Finger independence
When a person does not exercise there fingers to operate independently of the other fingers, they have the natural tendency to all move when one moves. This can be a problem for piano players. Finger independence keeps a player from hitting other keys accidentally. We have to do workouts for our fingers that give them the strength to curl and extend without the aid of the other fingers or the rest of the hand.
3. Hand independence
The piano is an instrument that allows a musician to play both the accompaniment and the melody at the same time. The musician hast to be able to concentrate on each hand separately as they move against or apart from one another.