Press upwards, keep elbows at 45 degrees. Mistakes: Arching back, uneven press.
Keep back against support, press evenly. Mistakes: Overarching back, uneven press.
Control the descent, squeeze at the top. Mistakes: Overextending arms, not controlling the weights.
Lift to shoulder height, control the descent. Mistakes: Swinging weights, lifting too high.
Extend arm fully, keep upper arm still. Mistakes: Using momentum, not fully extending arm.