The first thing I would do is gather, read, and analyze all information that is available, written, or verbal (talk to people!).
And for this, I would start with the org chart. It should show you, key stakeholders, to consider (and talk to). I would put effort to understand the environment (your project as part of the total picture) to understand your level of freedom.
Next, I would find out whether it has a set approach, or should you adapt your project methodology? For Software applications and requirements, agile concepts might be appropriate.