Top of the Tongue - Efficiency
Here's my personal approach to playing the harmonica...
1) Tilt face of harmonica slightly downward (around 30 degrees)
2) Open mouth
3) Insert harmonica, bringing the harmonica to the tongue (not the tongue to the harmonica)
4) For a standard tongue block (single note at right, with lips over four holes and tongue blocking three holes to the left), the tongue moves just one click to the left (11 O'clock)
5) To tongue switch, move to the right to 1 O'clock
6) To play an octave, center the tongue and use a lighter touch
7) To cover all holes for a pull, push lightly onto the face of the harmonica
It's very efficient (fast) and relaxed (very light touch at all times)... give it a try.