Being able to look closely at other photographers' images and pick apart what is shown, what each element represents and how it could be interpreted in multiple ways, is one of the things that makes a really successful photographer. This is because it helps you to be analytical of your own work. But it takes practice...
The 7 Questions
1. Who or what is the picture of?
2. Is there a focal point of the photograph?
3. What is happening in the picture?
4. Where was the photograph made – what is the setting?
5. When was the photograph made – guess a decade?
6. Does the photograph capture a particular or special moment in time?
7. What do you notice about the photograph’s composition (the use and placement of the visual elements: line, colour, tone, shape, light etc)?
Examples of different levels of analytical writing:
Image Analysis #1

'Revenge of the Goldfish' by Sandy Skoglund.

What do you make of the image above? Have a go at analysing it, considering the following:
• What does the image depict?
• What can you say about the composition of this image?
• Is it realistic, or surreal?
• What is the mood of the piece?
• What do you think the story is in this scene? What has happened? What is happening? What is going to happen?
• Do you think the title of the artwork changes how you interpret the story?
• Why do you think is everything blue, apart from the fish?
• Is there anything sinister or inappropriate about this image, or not? How might it be 'read' in different ways?
Image Analysis #2

'Famine Victim' by James Nachtwey

You have most likely seen photographs of people suffering with famine, but this image has become more iconic than most.
• What do you think makes this image stand out?
• What has the photographer done to alter the mood of the image?
• Would it have created a different story with different framing, lighting or had it been in colour?
• Do you think the photographer did anything to this image in post-processing/Photoshop? If so, what? And why?
Image Analysis #3

Boy Mid Flight by Steve McCurry

Steve McCurry often speaks about the decisive moment in photography, but how frequently do we encounter a shot like this?
• What has the photographer done to add movement to this images?
• How do the red hands on the wall influence your interpretation of what's happening here?
• Do the colours have a significant role in the way you view this image? Would it have worked in black and white? Why? Why not?
• How does the lighting in this shot influence the composition?
Image Analysis #4

The Decisive Moment by Henri Cartier-Bresson

The first one from the great master himself, many photographers consider this to be one of the finest street photographs you could find (it is certainly one of the most famous). The image here is an ultimate example of what was later pronounced as the decisive moment. Henri-Cartier was possessed with this specific habit of shooting photographs with a great sense of timing. 
• What do you think makes this image so iconic?
• What else is successful about this image, other than the timing?
• Do you think the same sort of image would become as iconic nowadays? Why? Why not?
Image Analysis #5

Photo by Saul Leiter

This photograph asks a lot more questions than it answers.
• Where was the photographer?
• Who is the man in the centre?
• What is happening outside?
• The window creates a barrier between photographer and subject. How does this influence your interpretation of the image?
• What do you think works well about this image?
• What do you think doesn't work so well?
• Many photographers would say this images is over-exposed. Do you agree, or does it add to the effect the photographer wanted? 
• Can you think of any other 'rules' the photographer has broken?