Landings
After several hours of general handling practice you have learned to relax and you feel confident that you can handle the aircraft with a reasonable degree of competance.
Now you are trying to develop a new skill at the point where you feel it may well hurt if you get it wrong, so quite naturally you tense up. That results in jerky control inputs and over / under controlling.
You must relax. Don't worry . This phase is perfectly normal for most students. It will come, and when it does you probably won't realise what you are doing differently. It will be the smoother, gentler and more accurate control inputs making the difference.