Taking just one photograph is part of a suite of exercises which will need to done in sequence. Taking just one is the first of these. After you complete this exercise continue on to the next one. Before you leave home make a frame that is the same proportions as your preferred aspect ratio. You see I prefer working square at the moment so I would make my frame square. If you like to play around with aspect ratios you can easily make ones with two L frames so that you can easily vary the aspect ratio.
This exercise works well in a landscape setting. You may not need wilderness but I do recommend a quiet park or bush land setting. Somewhere that is a nice walk in to get there is a good thing, as this will let you settle your mind and prepare you mentally for your task on arriving.
When you get to your spot, one where there are multiple visual possibilities, rather than just one like at a major lookout. Find a good spot where there are some great photographic opportunities and take the next hour to sit there and look.
I want you to sit there and look for that whole hour without taking using your camera and take lots and lots of photographs in your mind. Frame them up using your frame. figure out what they look like in your mind when they are printed. Work on the composition of each. Figure out which lens you would use. The further away the frame is from your eye the longer the lens you will need. The closer it is to your eye the shorter the lens you will need. You can figure out this exactly. (link)
Take lots of photographs in your mind. And figure out which one is your favourite. The best one. The one that stirs your emotions. You have been given the hour to make your mind up. If you make your mind up in the first ten minutes I want you to still sit there and keep looking, just in case you find a better one.
Now you can get your camera out and take that one image. I suggest you put your camera on a tripod to frame it up exactly. You are allowed to take a few frames, bracketing your exposure and your focusing, but only of that one frame.
Take it home and download it to your computer and process the image.
What was that like? How did you feel having to sit there and just look? How hard was it to just take one photograph? Are you pleased with your photograph? Do you think you would take a different photograph if you were to repeat this exercise. Make notes of your thoughts.