The Tamil script, one of the oldest classical writing systems still in use today, is critical to the cultural identity, communication, and heritage of Tamil-speaking populations around the world. Despite its global prominence and historical growth, Tamil typeface design is underdeveloped and poorly documented, particularly in comparison to the solid typographic systems of Latin scripts. This study addresses a fundamental methodological vacuum in Tamil typeface development: the lack of a documented, theory-informed, and replicable design process. Using the Systematic Literature Review (SLR) method, 24 peer-reviewed sources published between 2000 and 2025 were analysed. The findings show significant deficiencies in process documentation, theoretical integration, tool utilisation, and usability testing. In response, a six-phase design framework is developed to provide structure and consistency for future work. This framework merges historical context with visual communication theory and practical application. By addressing the methodological gap, this study enhances the usability, consistency, and cultural relevance of Tamil typefaces.