In order to improve the design of procedural instructions, technical writers need to know how users proceed when they are using them, from their initial reading, to execute described actions. Several kinds of activities are implicated, such as reading with understanding, action planning, carrying out specific actions, and executive control activities. This paper proposes that by taking into account design factors that affect these activities, technical writers can markedly improve the design of procedural documents. Thus, a model is suggested that combines information on how users deal with procedural documents when faced with new equipment and the mental processes involved in this interaction, together with document design recommendations aimed at enhancing the interactions between users, documents, and equipment.