The disclosure and misuse of personal information are two major problems of social networking sites. To address these problems, several models focusing on trust or privacy have been proposed. We propose a privacy model addressing the following issues: What could be private? For whom is it private? When is it private? And how can it be made private? We also propose a trust model covering five aspects related to what could be trusted, when it could be trusted, where it could be trusted, whom to trust, and why to trust someone/something. In addition to leveraging results from current research works on trust and privacy, our models are based on the results of our survey that we have undertaken to analyze the responses of users to friendship requests from unknown individuals and to conduct a comprehensive gender-based analysis of the collected data.