There's always this discussion before PS. The general consensus on SAF is that you shouldn't prepare in that aspect. Let Plebe Summer do its work and you'll be fine. If you study before hand, it will be obvious that you prepared and it will make you seem snobby and make your classmates look bad.
But if you really, really want to, then memorize the first 8 laws of the navy, the rifleman's creed, the man in the arena, invictus, the qualifications of a naval officer, marine corps and navy enlisted ranks, the 11 orders to the sentry, and the chain of command. Again, though, it's not really recommended.