How do you design a modulo-N counter using standard flip-flops?

A modulo-N counter counts from 0 to N-1, then resets to 0. Design methods: 1) Truncated sequence: use enough flip-flops for N states and add reset logic when count reaches N-1. For mod-6: 3 flip-flops with reset when Q2Q1Q0 = 101. 2) Preset method: load specific value when terminal count reached. 3) State machine approach: design next-state logic for exact sequence. Considerations include glitch-free reset, synchronous vs asynchronous reset, and handling of invalid states for robustness.