Criss-cross your legs to find a more stable base... and a consistent strike
One of the most common chipping errors I see is golfers trying to help the ball up, into the air. It gives a saggy-kneed look to the action, as the player drops down in an attempt to get below the ball and help it up. The move produces an ineffective attack angle, compromising strike. Instead, you need to trust the club's loft to create the height you need, and focus on creating more of a down-and-forward strike from a solid base. Here's a simple drill to help.
Fault: Poor shots by trying to help the ball up
Fix: Create a more solid base, and hit down and through
The issue: Backward step
Try to help the ball up and you'll adjust to get 'under' the ball. Your weight falls back and your knees tend to collapse. The club bottoms out early and rises through impact, causing duffs and thins.
Step #1: Knees locked
Take this cross-legged stance, your trail leg wrapped over the front of your lead leg. This locks your knees together; they can't collapse or sag from here. Make your regular backswing.
Step #2: Consistent strike
Now, simply strike the ball. Initially you will struggle to make solid contact. But persevere and you'll begin to feel how this more stable base allows you to train a more consistent, level strike.