For clear software architecture diagrams, start by choosing the right type of diagram (e.g., sequence diagrams for API documentation, ERDs for database schemas, flowcharts for user flows). Use expressive icons where possible but ensure they are easily understood. Focus on defining nodes, groupings, and connections. Avoid trying to cram too much information into one diagram. Use AI tools or modify existing templates for quick starts. Consider UML and C4 for detailed standards.