Sheetali and sheetkari are both slow, controlled breathing techniques that have a cooling effect on the body. These are the only two techniques in pranayama that involve inhalation through the mouth.
Sheetali
To perform sheetali, first stick the tongue out fully and curl the side to make a tube. Then inhale slowly, deeply, and fully. Withdraw the tongue, close the mouth and exhale through the nose slowly and completely.
Now do 3 rounds of 10 inhalations/exhalations with a 30 second break in between each round.
Sheetkari
Sheetkari has the same effect on the body as sheetali (i.e., cooling) but the technique is slightly different. To perform sheetkari, first gently close the teeth together and place the tongue behind the back of the front teeth. The lips should be open as if smiling (teeth closed). Then inhale slowly, deeply, and fully through the sides of the mouth. Close and relax the mouth and exhale slowly, fully and completely through the nose.
Now do 3 rounds of 10 inhalations/exhalations with a 30 second break in between each round.