Abstract Extreme torque and drag (T&D), especially when unplanned, is a primary limiter to the reach of horizontal and extended-reach wells. Many engineers use T&D software models without a thorough understanding of how the input affects the calculations in the program. This paper describes best practices in complicated T&D modeling applications. The discussion in this paper is applicable to wells with horizontal laterals, extended-reach wells, wells with difficult geometries, and all complicated well operations that require T&D models for planning and troubleshooting. Specifically applicable are operations that T&D programs have difficulty handling, such as running dual strings, expandable casing operations, drilling with casing, and jarring operations. Most engineers involved in downhole operations from operators to service companies run either T&D models or base decisions related to their wells and operations on reports from these programs. Many of the engineers and managers in the oilfield can benefit from this guide on best practices for a commonly executed, but little understood, component to well planning. Few papers address the practical application side of T&D modeling, and most engineers and managers have only a basic understanding of how to create a model or interpret the results. This paper disseminates technical information to increase global competence in a vital part of any challenging well drilled. Drilling extreme and challenging wells is becoming more common, and increased knowledge for T&D modeling and interpretation is needed.