You've already gotten quite a few good tips, and research is key here.
Your post brought something else to my mind, though. You say they are separated only by a fence, and I would be surprised that a very big "rich quarters" house be right next to a poor area like that. Society tends to isolate its poor areas. However, that doesn't make it impossible.
Either you can just work with symbolics, or do some research about this: Some very poor people might not seem like it. They have a big house which might have been passed down, bought before a big financial problem or bought for a huge debt, and their money all goes into paying the house and taxes, leaving very little for food etc, so they struggle to survive without necessarily getting any trouble for debts. They live in a big house, but with the bare minimum inside, often makeshift furniture made out of boxes etc. I haven't seen this first-hand (I was told about this by someone who distributes help to the poor and was surprised at first to be sent to such rich areas of town), so I couldn't give you much more details, but it could be something interesting and different to show, if you can find out more.
Of course, you don't have to use this, but I hope it sparks your imagination and inspiration. Good luck with your story! If you do good research, you don't have to worry so much about cliches. Just write the story you wish to tell.