Specifically about shape and position of the tongue.  A large, broad tongue is not a sign of good training.  We are not supposed to "take the tongue apart " here with a lecture on the very interesting and varied details of the tongue muscles. But we need a controlled tongue position in our mouth; and since the tongue is made up of muscles, her muscles must be well under control. There are many training exercises on this topic, also on the website in the exercise directory  http://myonet.de/BUCH/buch-word/ueb-word-www/contents-e.htm  . Here we should just keep in mind that the tongue holds the ring lightly against the POINT when holding the ring. Whith Hold & Pull, or  Hold & Swallow the tip of the tongue must then press the ring firmly onto the POINT (or the ring is gone). Later in the swallowing process, it should also squeeze the food backward like in a tube of toothpaste.