The 100-breaker’s typical fault is to start down too aggressively with his upper half; the 80-breaker tends to over-use the lower half. The 90-breaker could adopt either of these errors.
His best strategy is a neutral approach, a square face delivered straight down the line. For this he needs to set the face at address appropriately and develop a co-ordinated attack on the ball where the armswing works with the body turn.
You need to unify the arms and body so they make an equal contribution to the strike. Pin an iron across your shoulders and take up your normal address posture. Make sure the aim of the face matches your spine angle.
To establish a neutral blade aim at address set the shaft in this horizontal position, hands opposite your chest. Check your left arm and the face are in line; the blade is now square.
Rotate your shoulders to mimic a downswing. Keep the club pinned to both shoulders as you turn. Let body rotation move the face into position. Feel connected between arms and body.