They typically hire through University recruitment, i.e. Career Fairs, BAP, On-Campus events.
You should be active on campus and networking with the recruiters and other accounting students.
Prep a flawless resume and be prepared to sell yourself at those types of events, and if they like you, you will be offered to interview.
Interview 1 – Is typically an on-campus (or sometimes on-site) interview. It is behavioral based.
Interview 2 – Is typically on-site (and in groups) where you interview with multiple members of the firm, i.e. Partners, Directors, Managers, and/or Seniors.
If you fit in, and sell yourself enough, you can expect an offer.
FYI – Big 4 usually hires out at least 6-12 months ahead of the anticipated start date, so be sure to acknowledge that and plan accordingly.
That is all.