What purification practice cleanses the nose and the sinuses?

Pour the salt water into the Neti pot and place the spout of the pot into one of the nostrils, say the left nostril. The cone at the end of the spout should to be placed inside the nostril.
Tilt your head gently and open your mouth (Breathing should be done through the mouth during the process). Adjust the tilt of your head up to a point where water starts flowing from your left nostril to the right nostril. Continue till the water in the pot is finished.
Fill the pot again with salt water and try the same procedure from the other nostril (say the right nostril).
You can repeat this process any number of times, depending on your need and time.

Neti or Nasal Cleaning can also be done with milk. It is then a called Dhugdha Neti. There is another practice called Sutra Neti. In Sutra Neti, a waxed cotton string is inserted into the nose and pulled out from the mouth. Cleaning is done by to and fro motion of the string. Instead of using cotton thread, a rubber catheter may also be used, as it is convenient and easily available in any medical store. Benefits of Sutra Neti are similar to that of Jala Neti