Here are some practicing tips for:
The wrist should be level with the arch of the hand so fingers only have to bend slightly to play.
When playing, avoid dropping your wrist below the keyboard level.
Elbows should be level with the height of the white keys. If this is not happening, adjust the seat or add pillows or books to make it happen.
Start with scales to warm up and loosen up.
Sing your pieces to help learn them. Try to move to your singing too.
Visualize the piece.
See the music in your head.
If you cannot remember a place, mark that part of the music in colored pencil and study that part. Visualize the piece 3xs each session.
Performing - Piano
Leave time to at least run your hands over the keyboard of a different piano to feel its weight and resistance.