When purchasing medical insurance, it is crucial to carefully review the policy's fine print to avoid unexpected costs during hospitalizations. Key areas to scrutinize include the 'not covered' section, understanding exclusions (both permanent and temporary), and clarifying waiting periods for pre-existing conditions or specific treatments. Additionally, policyholders should be aware of potential out-of-pocket expenses like deductibles, co-payments, and sub-limits, which can significantly impact the final cost of care.