LCD monitors are getting bigger, better and easier to read. My original Pentax Optio WP has a 2" LCD monitor while the newest Optio W10 is equipped with 2.5" low reflection LCD monitor. The LCD cover is finished with a non-glare coating, making the screen easier to see even outside on a sunny day. The new Olympus Stylus WS 720 also features 2.5" LCD display. Do not use sunglasses when shooting. It's easier to see the digital display without them.
Shooting pictures with a digital camera is cheap. You do not need to worry about film cost. You can always erase the picture and shoot again unless you are after some action shots. So, do not be afraid to experiment and shoot even if you do not see the image in your LCD monitor. Shoot some extra frames. It is helpful to have an adequate memory card.
3. Practice! You will get a feeling what's in your frame even if you have troubles to see the image on the LCD display.
4. I wouldn't shoot pictures with the viewfinder from a tippy racing kayak or surfski. I prefer to shoot with extended arms using the LCD monitor. In my Sisson Nucleus kayak I do not like to drop a paddle from my hands unless the water is really calm. Since my Pentax Optio is tiny I use the paddle to stabilize the camera for shooting. In the case of my kayak, this approach helps me to stabilize both the camera and the kayak, and the paddle is ready for bracing. You need to keep your camera on a leash.
5.Be creative! Shoot from different angles wherever you can reach with your arm. If you have a waterproof camera, experiment with shooting close to water surface, underwater or with a partially submerged camera (see my picture of Sea Wind with a sail above and the picture by Timo Ripatti).
6. Shoot self portraits! You cannot use the viewfinder in these shots anyway.