When negotiating salary in Big 4 firms (Deloitte, EY, KPMG, PwC), research the market rate for your role and industry. Know your worth and be confident. Start with a slightly higher target salary than your desired amount, as this gives room for negotiation. Emphasize your skills, experience, and achievements. Be flexible and open to creative solutions, like additional benefits or a performance-based raise. Be professional and respectful, and be prepared to explain your request. Remember, negotiation is a conversation, not a confrontation. Good luck!