Ask HN: Best skills to land a job at Big 5

Coming from a mediocre no-name university but decent programming skills, what would be some of the good ways to land a job in any of the Big 5 companies? I understand coding test skills are essential for the interview, but this question also refers to the pre-interview skills. For example: Open source project contributions, e.t.c.

I have 6 months to rigorously prepare, enhance my CV (work on projects, e.t.c) and wish to optimise my learning path. Would having a personal machine learning research project be of any help>