It depends what part of ABFAS you are talking about... written is mostly stuff you already learned if you studied hard in school + residency, and CBPS is mostly knowing the options and format.
Didactics multi choice BQ stuff:
-Pod school, residency interview, residency academics info already learned.
-ACFAS lectures and JFAS journal.
-major textbooks (McGlam, Coughlin, Myerson, Easley, etc)
-PI manual
-the practice tests on ABFAS itself and BoardWizards
CBPS for BQ:
-same as above
-Board Wizards and ABFAS itself practice CBPS cases (go over the lists of choices many times, print them, search around in them, etc)
BC Case review (these are jokes... maybe):
-take better care of your notes than your patients
-replace any long screws even if it means losing fixation strength
-never document any edema or pain after a month or two post op in case the patient does not f/u anymore
-always remember that clinical outcomes matter little... it's all about chart and radiographic perfection since it's not f2f
-don't do MIS or dynamic fixation or anything outside the norm because "standard of care" will often mean only most common type of fixation/proc for the pathology to a random reviewer who typically trained years prior
-commit HIPAA violations to take patient notes, XR screenshots, hospital op records, etc if you need to ever leave a job while BQ
Good luck.