what the others said, plus:
Use the brc self assement tool / auditor check list. Be honest with yourself when doing so. Know how you will address each item. organize your program so that you can find / access policies, procedures, and monitoring records quickly. an auditor once told me that in a two day audit, they have ≈ 4 minutes to ask a question, you to provide the answer / document, them to review the document, them to record. they get angry when it takes too long for you to provide evidence.
make sure all employees are trained well. they need to be able to answer simple questions regarding there roll in haccp /ccp monitoring, sanitation, gmps, allergens, brc/gfsi, non conformities, etc