One thing about photography is that you have to practice. This may sound obvious, but it's amazing the number of people I meet who only pick up their cameras just before dive trips.
Practice means having your camera with you and taking pictures of whatever you come across. It doesn't mean having to dive all the time if your primary interest is underwater photography.
Take this bird for example. I took my camera out yesterday when I went for a walk to take in some fresh spring air.
I came across this bird hunting for fish in a tiny pond in the middle of the city, surrounded by urban sprawl.
I watched as it missed several times. With practice, of course, it no doubt caught a meal at some point, just like it took me a few flubbed shots to get a decent photo of this bird. (My knowledge of birds is woefully inadequate. Can someone tell me what this is?)
This isn't the world's greatest bird image by a long shot, but taking the photo gave me an opportunity to forget the rest of the world for a moment, watch a beautiful bird go about its business, and practice framing a simple shot in an incredibly cluttered environment.