Effective software cost estimation relies on essential metrics to enhance project success and avoid estimation pitfalls. Key metrics include project size, complexity, and scope. Understanding the size of the software, in terms of lines of code or function points, is crucial. Additionally, assessing project complexity by considering factors like technology, architecture, and external dependencies is vital. Scope, which encompasses features, requirements, and changes, must be well-defined. Ensuring alignment with project complexity helps prevent underestimation or overestimation, improving accuracy. Regularly updating estimates as the project progresses and using historical data for reference can further enhance estimation reliability and overall project success.