Technique C: Use Your Tongue
You can clear the backed up sinuses using the finger and the tongue as well. Press the tongue on the roof of your mouth hard and press the finger on the skin between your eyebrows at the same time.
Hold for 15-20 seconds in order to stimulate the flow of mucus out of your head. If you have not loosened the mucus entirely, you should alternate between pressing the roof of your mouth and the skin between the eyebrows for 10 seconds each!
The following video will provide additional guidance on this method: