There's a trick I learned for clearing a stuffy nose.
Place the tip of your tongue on the roof of your mouth. Then, place a finger on the bridge of your nose.
In very small motions, alternate between pushing up on the roof of your mouth, and then releasing that and pushing on the bridge of the nose. Use a gentle teeter-totter to rock the pallette. Repeat ten or so times and, within a few seconds, your nose will be open.
Right below the divide between nose and face, so about 3mm or so. In fact, if you press up on the roof of your mouth you'll feel the spot on your nose very slightly rise up.
Essentially you're rocking the soft palette up and down which flexes the sinuses and opens them up.