My advice would be:
1. Stick on a Metronome to a comfortable tempo
2. Practice picking on the clicks (quarter notes) then 2 picks per click (8th notes) then 4 picks per click (16th notes) - Make sure than your grip on the pick is super relaxed during the whole thing.
3. Have your wrist move in the smallest comfortable distance that you need for what you're picking (economy of motion)
4. The minute you feel tension in your arm of forearm, let it relax completely, count to 10.
The most important parts are that you're relaxed and are playing to a click as much as possible