Hi, here are my two cents:
1. If you're uke is a beginner, don't go too fast. If a newby uke feels some control he becomes more confident. Remember that a lot of newbies are only thinking about which feet to back first when they fall and keep their head up and lot's of other thinks they have remember while falling.
2. If the uke is bigger, don't pull his head down with force. I'm 6'4'' and someone is pulling my head down I stop dead centre. This is a natural reaction especially for a newby uke who maybe doesn't understand what's happening.
3. Don't go into those pressure point things on newbies, but instead ask him why he stops and explain his role to him (again and maybe again). Use more experienced people to play with pressure points. It's fun isn't it 8^)
Luck to you all,