Collaborative Question Answering (cQA) platforms are a very popular repository of crowd-generated knowledge. By formulating questions, users express needs that other members of the cQA community try to collaboratively satisfy. Poorly formulated questions are less likely to receive useful responses, thus hindering the overall knowledge generation process. Users are often asked to reformulate their needs, adding specific details, providing examples, or simply clarifying the context of their requests. Formulating a good question is a task that might require several interactions between the asker and other community members, thus delaying the actual answering and, possibly, decreasing the interest of the community in the issue. This paper contributes new insights to the study of cQA platforms by investigating the editing behaviour of users. We identify a number of editing actions, and provide a two-step approach for the automatic suggestion of the most likely editing actions to be performed for a newly created question. We evaluated our approach in the context of the Stack Overflow cQA system, demonstrating how, for given types of editing actions, it is possible to provide accurate reformulation suggestions.