Is the judge harder your images, indulgence leads to conformism and mediocrity, the competition more large is against yourself.
Studies the composition of photography techniques and clear this painting (never others read about the great painters were the photographers of antiquity).
If a school of fish photos, search is polarized areas which are more ordered, it is not easy but it is worth.
Always shoots from an angle to
level or low in relation to your subject.
Patience, plan to your image, takes the picture before, accept your mistakes, improve them a perfect photo is the result of many good photos.
Do not give up before the first frustration, many will come more.
Get the juice to your camera options, experience and experience.
It exploits all angles of the same photo.
Always check the work of great photographers in all specialties there is something to learn.
Known habits of life of your probable subjects to photograph, I go back and insist there is much to read.
Think as a photographer, he lives as a photographer, he sees the world as a photographer. Every day has something for your photographic skill, practice, learn, learn new techniques, behaviors, history etc. always there is something related to your hobby to make while are not under water.
Learn how to break the rules and walk you through your heart, do not try to copy the work of others, you develop your style.
There is much more to be done when it comes to underwater photography but these tips I am sure that you will be very useful. greetings and Aguas Claras.