Writing a Project Proposal on an Online Job Portal with more advanced features, a rating system for both employers and job seekers(For employers to rate Job seekers who have worked for them and same for the employees to rate employers. Also an option to upload Video Resumes and have Video Interviews scheduled on the platform.

I need any help i can get on the best most suitable METHODOLOGY to be used on this. And why? Also if i can get help putting together my Functional Requirements and DFD.

Thanks.