Don't photograph your bubbles, or those of another diver, unless you want them there for drama. Time your shutter release for when you're inhaling. Be patient and keep your subject in the viewfinder. If the subject is hiding in the coral, just be quiet and wait for it to appear. Then you can snap the photo.
Buoyancy control is very important when taking pictures underwater.
Proper control will allow you to hang suspended in the water while you frame the perfect photograph. After the dive, rinse camera and other photographic equipment in clean fresh water. This is especially important when diving in salt water, as in the Caribbean. And remember to develop film promptly after you return. Bring extra film, batteries, and o-rings for camera and flash.