Have your camera on you an ready to shoot.
One of the most common reasons for not getting the really good fishing images is that people simply don't bring their camera. Either it's left at home - which is really stupid - or it's left on the bank or beach - which is just moderately stupid.
If you want to take pictures you need to have the camera with you and on you.
Let's assume that you at least have brought the camera on a fishing trip. That's a good start. The next natural step is to have it on you while fishing. Situations worth photographing appear and disappear within minutes if not seconds, and if you're not ready to shoot quickly, it's all gone.
Envision this: Your friend is fishing next to you. He or she hooks a fish.
"It's a nice one! Can you get a picture?"
Sure you can... you just need to reel in your line, wade in to the bank, drop your rod, unpack your camera and wade back. If your friend is a considerate angler that fish has been fought, landed and released a long time ago.
If you have your camera on you, you won't only get the picture of the fish, but also of the fight.
Another reason for not getting the pictures is that camera-owners are too careful with their cameras. No matter how good the weather is and how safe the wading is, they wrap it in three layers of zip-lock bags and put it in a camera bag. Some of these bags are even referred to as "everready" bags. If there's one thing they aren't, it's ever ready!
Put your camera inside your jacket or waders and don't wrap it in anything but put the strap around your neck or attach it to your waders. The risk of dropping the camera is far greater when unpacking it than when just pulling it out and using it. And the less handling, the safer it is and the quicker you get your pictures. I have bought a giant retractor meant for landing nets, which I use for my compact camera - which by the way has been in the water three times and still works fine.
And do also take pictures in rain, sleet and snow! Images taken under these circumstances will usually come out excellent, and since such pictures are rarely seen, they often stir a lot of interest.
If your camera is an ordinary non-waterproof or non-splash-proof one, just haste with the job to avoid too many drops on (and above all in) the expensive equipment.
You can visit 500th.net, which has much more on photography.