Preparing for a new client in the healthcare field includes a detailed intake form followed by a consultation. I'm a chiropractor, so our job is to listen and ask even more detailed questions about the patient's history and current complaints. When appropriate we move to physical examinations gathering objective information, and noting any trauma, toxins, and thoughts influencing the patient's health that will ultimately help us render the best care for the patient's current situation. Sometimes we have to be prepared to refer new clients for imaging or to specialists that will better fit their needs. 
Working with patients recurrently, the standard is to review important past health information, including any clinically relevant new information, and most importantly monitor the progress of the patient's complaint throughout the care plan. Not every case is the same and although we might see 50 low back pain patients, important details contained within the previous steps will confirm or reveal the most appropriate diagnosis and plan for care.