Re: relaxing during technique - how?
I have had success with getting people to relax more by using breathing. Start by long slow breathing a few times, then for example, with something like shiho nage, breath in long and slow while lifting and turning, and breath out long and slow while dropping your hand.
Good for uke to practice the same long slow breathing too.
The other suggestions, particularly around relaxing the mind, and very to the point, though perhaps not so easy to actually grasp!