A few more ideas to add.
Focal point: woman in red dress is the
dominant object within the image as she is brighter, larger and clearer/more distinguishable (colour, placement, size) than the other people. The other people are all mesmerised/possibly intimidated by the woman and are all looking at her which suggests she is being judged. This could suggest she is not congruent with the dominant group/lifestyle etc, further implying her alienation.
Clothing: the clothing of people implies the main woman has a higher socio-economic status than those around her. She is wearing is clean, red, decorated, 'going-out' dress while the others are wearing dirtier, colourless, crumpled, 'stay-at-home' clothes. Her social/economic status makes it difficult for her to integrate into the group.
You could go all out and say she does not belong because she is not prejudiced. The others are studying her, looking for human weaknesses while she is staring at the surroundings (I think). She is interested in the physical environment which is a stark contrast to those around her who are more worried about the flaws of humanity/finding weakness/making false judgements.
The woman is the antithesis of the rest of the group. She is familiar with people but confused by her surroundings whereas the others are familiar with their surroundings but confused by the woman (person). Refer to facial expression, body language.
I'll stop there: my analysis is weak/generalised but in terms of
techniques it is what you should look out for.
Just realised you would have finished this task a month ago.
To Harriet: sometimes the better related texts are the simplier ones which can be analysed thoroughly to create complex, symbolic meaning - and the techniques are easier to pick up on too!