Handling NULL values in SQL is context-dependent and requires a tailored approach. Five effective ways to work with NULL values are: using COALESCE for default values, ISNULL and IFNULL for simple substitutions, handling NULLs in aggregations, leveraging CASE statements for complex logic, and building NULL-aware joins and filters for data quality analysis. Each technique has its own advantages and considerations, and choosing the right one depends on the specific use case and required level of complexity.