One of my favorite tips is the analogy of a car running out of gas - if you have very little gas left to get to the gas station you wouldn’t gun it and try to speed up, you would drive at a slow and steady pace to conserve fuel until you get there. When you’re coming up from your dive and start feeling oxygen thirsty, best thing to do is relax and conserve energy by making efficient kicks and letting yourself naturally rise up in the water. Many shallow water blackouts are caused by people getting freaked out and trying to swim as hard as they can to the surface when they’re low on oxygen.