Existing indoor navigational aids such as signs and floor plans are originally designed to assist navigation and to support spatial learning. However, they are often neglected in current navigation services. Integrating such information adequately into indoor navigation services requires a better understanding of their usages. Thus, we conducted an empirical study in two buildings with 28 participants who had to think aloud while performing wayfinding tasks. By analysing the participants’ verbal protocols, we distinguished two decision making scenarios and suggested categorizations of their indoor wayfinding tactics. Our results confirmed people’s reliance on existing indoor navigational aids and indicated that signs were the most commonly used aids. In addition, the characteristics of targets influenced the choice of aids. Therefore, we recommended that indoor navigation services include signs and present route information adaptively based on distinct destinations.