Step and turn two. The most common mistake here is losing eye contact with the target. Be sure you keep your hands together and high. There are 2 ways to get here. Pick the leg or swing the leg.
Pickers have better control.
The higher the leg at three the faster the fastball. Leave high three by bending the back knee, so you can drop and drive. Square up everything as the front foot lands. Make a 90 degree angle with the arm to side, at the elbow and keep the wrist straight and loose. Finish in a low fielding position to protect yourself and to make your delivery consistent.