When i try to fast pick my pick with hit the string and ill stop in the middle of it. How can i improve ?
Have less pick showing under your thumb.
try lots of picks until you find a thickness and material you like, also try lighter gauge strings
you can try adn angle the pick a bit so when it hits the string its not the flat part but rather the side of the pick hitting the string, so it will kinda slide on the string.
As Daron Malakian has said, "Masturbation is great for the right hand."