StackOverflow (SO) contributors are recognized by reputation scores. Earning a high reputation score requires technical expertise and sustained effort. We analyzed the SO data from four perspectives to understand the dynamics of reputation building on SO. The results of our analysis provide guidance to new SO contributors who want to earn high reputation scores quickly. In particular, the results indicate that the following activities can help to build reputation quickly: answering questions related to tags with lower expertise density, answering questions promptly, being the first one to answer a question, being active during off peak hours, and contributing to diverse areas.