Build an External Memory System

I constantly forget important things like [List of frequently forgotten things, e.g., 'replying to important emails', 'project deadlines', 'taking my medication', 'birthdays']. Help me design a 'bulletproof' external memory system. It should be based on a combination of digital tools (like [e.g., Google Calendar, a specific app]) and physical cues (like [e.g., a whiteboard, sticky notes]). The system should NOT rely on me 'remembering to check it,' but rather use proactive alerts or unmissable placement.