Select a specific purpose and audience, based on a real-life situation at work or at school, and write out some concepts for how you would evaluate whether this situation is a suitable one for a formal report. List all possible audience/readers members and all possible purposes. List the types of questions your report will need to answer, and then list the types of research you will need to do in order to prepare the report.
After that;
Prepare a formal report using comparative, causal, or feasibility analysis.