I like to start the class or end the previous class with a koshi nage exercise; you place uke on your hips and uke relaxes allowing his limbs to soften along with his spine. You then place him back on his feet. I have always found that people are afraid of koshi nage, it does seem a very long way to the floor! I have found this to be helpful in overcoming uke fear.
As for the execution of Koshi nage, I feel that getting uke on to their toes is a good situation in which koshi nage seems to make sense to beginners.
Sankyo ura, at the point where it seems you are fly fishing ( uke is whirling around you on his toes) you step in and place him on your hips. Ryote Katate dori koshi nage is a good one, the arm going to the sky finds the yonkyo nerve uke goes to his toes place him on your hips.
The point I try to get across to my students when teaching koshi nage is to sink the body as the arms go to the sky and to raise the body when cutting.
And that it isn't a throw as such but you offer uke support on your hips and when he is supported you simply take it away.
Regards Paul Finn