Cloud Computing is an Internet-based business paradigm, within which cloud providers offer resources (e.g. storage, computing, network) and cloud consumers use them after accepting the associated agreements. The demand of a particular functionality can rapidly change in this paradigm, so organizations need to count with a method to elicit, analyze, specify, verify, and manage dynamic requirements in a systematic and repeatable way. Existing requirements engineering (RE) approaches for Cloud Computing are generally focused on a limited number of non-functional characteristics (e.g. security, privacy, performance), and service consumers have no guideline to cover multiple dimensions of a requirement in cloud environments. To address this problem, a conceptual model is initially presented to analyze cloud requirements and services. Then, a workflow is proposed for handling those requirements and supporting cloud service adoption. In this paper, we explain our contribution based on practical experience in projects and existing RE approaches.