These are the basic questions:-

• Have you suffered an injury? Injuries can be of different sorts, including financial, physical and psychological.
• Might someone else be legally responsible? This may be where someone else is negligent, but often the law imposes liability where the other person might not seem to be at fault.
• Would that person be able to pay. This is about recovering compensation - usually from an insurer. Extracting blood from stones is not the plan.
• Is your claim in time? Do not delay making your claim. The law imposes strict time limits.