If you are interested in becoming an attorney at another law firm, the first step is researching which firms have openings. You can do this on recruitment websites and through most law schools and associations that focus specifically on recruiting lawyers from other legal industries, companies, law firms, or countries.
To become a lawyer at any firm, you need two things:
1. Pass their rigorous testing process to prove your willingness.
2. Show them how good your expertise is (in resumes).