Just talk with your CTO(or person with similar post), arrange some meetings with lead developers and make list of some best practices and rules for structuring

Just talk with your CTO(or person with similar post), arrange some meetings with lead developers and make list of some best practices and rules for structuring files. Move one or couple of steps a time, review it in action and move ahead. Don't go on rushing to change existing codebase, spaghetti code is not what company's customers/clients are concerned. They are concerned about the end results. Starting good code practice will make legacy codebase dwarf at some point.