The world population is becoming older. Consequently, there is a significant increase in the number of computer users with more than 60 years old. At the same time, technological advances have allowed the emergence of a new type of interface, which uses non-conventional devices - the Natural User Interfaces. This work presents a set of guidelines for building Natural User Interfaces and their adherence to guidelines provided to build applications aimed to older adults. To evaluate the suitability of these guidelines, two case studies were created and used to perform an usability evaluation with senior users.