I suggest that the most appropriate way to go about this assignment is to compare two or more cases/countries (see fn. for sources on the comparative method-Review: Trochim, William M. The Research Methods Knowledge Base, 2nd Edition.Read everything under the heading DESIGN; Collier, David. The Comparative Method. In Ada W. Finifter, ed. Political Science: The State of the Discipline II.Washington, D.C. American Political Science Association.You can download the paper here: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1540884) The Syllabus has numerous examples of this approach. Of course, you may choose to focus on a single case, but you be sure to suggest in your conclusion how it informs our understanding of democratic erosion in general.
Refer to Purdue OWL guide for style format (Chicago) and for research papers/essay expectations.