Catasane,
When doing the small universe to start and to end the healing session, I always keep my tongue touching the roof of my month and I also ask the other person to do so. I see that as a full complete circle for the chi to move through the path of small universe. Just a suggestion to the other person, I don't insist on that. I also ask the other person to do the ending exercise after the healing session.
After the "openning" small universe, I focus on sensing the blockage and/or clearing the blockage. Keeping the focus on calling the Master's energy to help in the healing session and pretty much staying neutral as far as my facial expression. I don't think much about the tongue position but it is pretty much at the top near the teeth.
This is a personal opinion, I would not want to see a face with too extreme emotion, (happy, sad or anger ) or an uncomfortable one (forced facial expression) when someone is given me a healing session.
If it is difficult to follow through all that suggested then just focus on the loving thought that you want to help the other person toward better health.
