This document presents a systematic approach for creating accurate behavioral models for analog and mixed-signal system design and verification. The approach aims to reduce risks from model errors by collaborating closely with circuit designers to thoroughly understand circuit behavior. Key steps include automatically generating model shells, studying schematics, interviewing designers, developing circuit descriptions, validating descriptions with designers, and deciding which behaviors to include in models based on verification plans. The approach applies to modeling languages like Verilog, Verilog-AMS, and SystemVerilog.