It is important to keep proper hand positioning when playing the piano so here are some tips on how to maintain this crucial technique.

When you first put your hands on the piano, it is likely that your hands are tilting towards your pinky fingers.  There is a downward slope going from the inside of your wrist to the outside of your wrist.  This position is incorrect.  To get to the correct position, turn your wrists so that they are flat platforms.  Imagine that a drop of water is placed on the back of your wrists.  The goal is to keep that drop of water from falling off.  This hand position is what allows you to move your fingers quickly and easily over the piano. 

Once your hands are correct, take a look at your fingers.  Are they straight out or are they curved?  You want a soft, natural curve in your fingers at all times.  Even if a finger is not playing a note, you want to keep all fingers in this curved position.  When you do play a note, press the piano key with your finger tip, don't straighten out your finger and play with the pad of your finger.  Keep the soft curve through the entire stroke so your fingertips are pressing the keys. 

When both the hand position and the finger positions are correct, you will be able to play smoother sounding scales and songs, move your hands faster up and down the piano, and prevent any pain or injury to your hands or fingers while playing.  This technique will take some getting used to at first and may even make your hands and fingers a little sore, but keep at it and practice this position everyday and before you know it, it will come naturally and comfortably.