1. Learn Diving Skills. 

Underwater photography is not similar to traditional photography, you have to overcome the effects of buoyancy and control of where you are at all times. Besides, if you have not mastered the diving skills well, it will be a very tough challenge to get an ideal and well-composed picture. What's more, the most important thing is that you have to consider your safety. First the basics diving skills, if they're under control (buoyance, awareness) then you can begin to take pic’s underwater

2. Use the Right Camera Equipment. 

Compared with the camera, the lens and the underwater video light are more important. Water as you go deeper absorbs all the color. Therefore, if you think it's unnecessary to use underwater video light, you will get green or blue pictures. Most important, is good light or Flashes, I can’t compare the orca flashlights, but I would love to use them.

3. Choose Suitable Diving Gear. 

As the same as scuba divers, most open water underwater photographers need to choose diving gear for themselves. Such as wetsuits, fins,  scuba tanks, dive lights, etc. 

4. Study Marine Life. 

Familiar with the habits of marine life allows you to find how does the shoal of fish move and how can you get close to them, then help you produce stunning images. 

5. Suitable Camera Setting. 

As a photographer, you should familiarize some basic camera settings: white balance, ISO, aperture, shutter speed. The ISO controls the sensitivity of exposure of the sensor of your camera. Use the lowest possible. But with the new type’s you can shoot more than 800 ISO, but the most important is the light you can give by flashes

6. Familiar With the Rules of Composition. 

Master the rules of composition, including the one-third principle, the frame principle, the line of sight guiding principle, the movement principle, etc., and make full use of them in the shooting. This can help you take ideal photos easily. 

7. Wide Angle Lens.

We usually use the fish eye as our wide angle lens because it can give the widest possible view from as close as possible. Wide-angle lenses range from 10 millimeters to 24 millimeters as well as zoom or prime lenses. The wider the field of view of the lens used, the better it is to capture the complete picture of the environment. I use Fish Eye 10mm, reason, I take pics in the caves, no natural light, it’s hard, so I need good light / flash.

8. Macro Photography. 

A close focusing macro lens for taking close-ups from within touching distance. It is possible to shoot tiny creatures at close distances and present the details of the subject in detail, and at the same time have a very real sense of presence. I don’t take macro pics, with rebreather you can go closer

9. No Touch.

When you are diving or underwater photographing, please remember don't touch marine life. Respect for the ocean is an obligation as a responsible diver/underwater photographer. If we are honored to visit the underwater world, we should restrain our behavior. 

10. Have Fun. 

Diving is an enjoyable thing that you want to experience being immersed in an alternate universe, feel this wonderful moment you never have before rather than just to take photos.

The most important, if you don’t have fun with each dive, you will stop diving. The reason we go underwater, is to have fun.