Wearing the mask.
Any style mask will have adjuster buckles on both sides of the mask strap near the front for adjusting the tightness of the mask. The mask should fit snugly around your head and not be too tight or too loose. A well-adjusted mask should slide on and off the face fairly easy and not have suction when pulling it off. The pressure of the water will keep the mask in place by itself normally as well. Wearing a mask too tight can cause major discomfort around the face and also leave pressure marks on the face as well, and is not an enjoyable experience!