People who are blind can be at a disadvantage in social situations because face-to-face communication relies heavily on non-verbal cues. Lack of access to cues such as eye contact can sometimes lead to awkward situations, such as answering a question that was directed to another person. This problem is compounded by the fact that sighted people are not always aware of their use of these nonverbal cues, and they do not take this into account when communicating with people who are blind. In the long term, this can limit employment opportunities for people who are blind, can adversely impact their professional advancement, and can even isolate them. To address this problem, we propose a methodology for determining and enumerating the most important needs of people who are blind, as they interact with others in social situations. Next, we establish design guidelines for building a Social Interaction Assistant to provide access to essential visual information during social encounters for the visually impaired. Finally, we use our design guidelines to develop a wearable Social Interaction Assistant prototype that is aimed at providing this essential information in real-time, during social interactions.