I find that the best preperation for most any flight into an unknown area is to take the appropriate flight planning chart (high chart if one isn't available) and read every word on every panel as far in advance as possible. It seriously amazes me how much info is found there. (and how little pilots read it).
Second, go to international operations course at Scott IPC or FSI in Savannah. I recommend FSI Savannah because they have an instructor there that only teaches IOC.