Hoover here are a couple of procedures that I recommend to my students 1) once you have submerged take off your mask , open your eyes look around and take a few breaths before you replace your mask 2) after you have reached your planed depth help your self acquire a steady breathing rhythm , you can do this by inhaling for a four count and then exhaling for a four count ( this is a close approximation to how you breath when on the surface ) do this count as you breath for several cycles , hopefully this steady rhythm will soon become second nature 3) position your weights so that you can swim horizontally without fighting for trim , also do not over or under weight yourself .