As level Geog Edexcell, Need help!Watch
1. Background Information
3. Impacts (Split into social/economic/environmental and short/long term)
4. Solutions (Split into short/medium/long term)
Obviously the exact formula is slightly different depending on the precise case study.
One other tip I have is to only allow yourself to use two sides of an A4 page for your case study (unless your handwriting is huge!) as this forces you to condense your ideas down into easy to remember facts that will be of more use to you in an exam than massive paragraphs full of information.
I hope this helps, feel free to message me if you need more help!