Yes, I've got a special finger training device :)
pull my fingres backwards till i can feel presure then mimic opening a doorknob.
Occasionally. I pop my knuckles a lot if that counts. I sometimes wave my hands like some people do when they cramp. Just small things that really don't affect anything.
It must be always before you play the song
im stretching everytime im going to play, not only the hands, but also the arms