Hi Pekka!
Here's my method for doing the rings:
I go down to 5m (nice training pool in Munich) and lay on my back.
Then I wait for a few seconds and check the currents: the water should be very calm. I bring my head into horizontal position, pump air into my cheeks and then do a "Boo" (the lips form a circle).
It is very important to have no currents and to have your head horizontal. People often tend to slightly point their chinn in direction of their body in order to see what the heck is going on with those bubbles
- just relax and look straight upwards, to the shining surface
This works pretty fine for me...hope I could help you!
