Practice clearing a complete flooded mask by breaking the seal of the mask, and let it fill completely with water. Now, hold the top of the mask (by the frame, not the skirt) against your forehead, then slightly look up while you exhale through the nose. It is easier when you begin exhaling before tipping your head back, and exhaling steadily and continuously through the nose.
![](https://i.ytimg.com/vi/HGwXQmTT4Ms/maxresdefault.jpg)