What sort of teaching and/or thoughts can we provide to the student to allow him to realize himself that he's making these kinds of mistakes so he can try to fix it himself?
Thoughts are good if they instead lead to an appropriate example to provide.
So, they rush through a technique to get to the end and they're a little off balance. Balance and center have to be maintained throughout
is the thought. Impart that by being uke and grab their sleeve underneath and hang on after the throw. They will learn 'why' faster by discovering for themselves. Maybe they'll also see why lowering their center is good too. How they store this info is up to them.
I could have just said "Show them the consequences" of mistakes. Nothing more immediate than cause/effect.