If you hired a lawyer, they may do most if not all of the items for you. You should:
Obtain the police report from the local precinct who made the accident report
If your vehicle was damaged, ask your insurance company to send a property damage appraiser to give you an estimate of the cost to repair your vehicle
Keep a log or journal including the names and contact information for all medical providers you saw including all visits with dates of treatment. It may also be a good idea to jot down your complaints of pain. Keep copies of any diagnostic test results such as an MRI, X-ray, or CT-scan as these will help explain your medical diagnosis.
Keep a copy or list of your expenses incurred out of pocket due to the bus accident
Keep a record of days missed from work so you can file a claim for lost wages
Keep a journal or diary describing how the accident has impacted your life – what activities did you have to stop doing because of the injuries sustained.