Reputation systems provide a form of social control and reveal behaviour patterns in the uncertain and risk-laden environment of the open Internet. However, proposed reputation systems typically focus on the effectiveness and accuracy of reputation management, and suffer from a number of common vulnerabilities. As a result, introducing reputation management into the business environment may only replace the problems it hopes to solve with new issues. This paper aims to improve the security and robustness of reputation systems through 1) identifying the basic requirements in that area, 2) analyzing existing reputation systems for e-Commerce and a handful of other environments to compare their design choices and solutions provided, and 3) compiling a number of topical practices into guidelines for future research and development of reputation systems.