One of the first drills inflected on novice climbers is "silent feet." The objective of the drill is to place the foot quietly on each and every foot hold. It focuses attention on those strange objects on the end of the legs which are neglected in the novice climber's effort to ascend via a series of pull-ups. This drill can lead to rapid improvement because it provides immediate feedback (a super secret trick that can used to get better at anything). I have found it is slightly more effective when done in a climbing gym, rather than outside, because climbing on "plastic" is inherently louder than rock.
However, it can be have unintended consequences. In an effort to be silent, novices can put too little weight on their feet. This ingrains a different set of poor climbing habits. How can this be avoided? The best yin to the silent feet yang is "over-pressing" with the feet. After you place a foot, press it down with too much force. It often surprises how little force climbers were using in the first place. Later, you find the right temperature for the pressure porridge.
There should be a progression of two drills:
First, drills done separately on different days.
Then, both drills done on the same day.
Finally, both drills at the same time.