The most important thing (non-academically) is to bring a folder/clipboard that you can hold paper down with. I had half my SAC almost end up in a pond because I didn't do so
That aside, bring some binocular so you can observe primate physiological features in great detail. With some species, certain features (e.g. whether a digit is opposable or not etc) aren't immediately clear by looking at the animal cursorily. If the SAC is similar (or the same) to the one your teacher gave us last year, then make sure you fill in the table properly, as you'll need this in detail for ~90% of the write-up.
Try to be time efficient. We kind of spent too much time just casually looking at animals and were a little rushed towards the end of the SAC. Importantly,
know where the necessary enclosures are.
Content-wise, make sure you can draw a phylogenetic tree based on primate phenotypic features. Know what distinguishes primates from each other (e.g. how are chimpanzees different from humans), the difference between hominids and hominins, evolutionary features of humanity (like uprightness and what caused it). Understand why evolutionary features such as opposable thumbs were beneficial etc. etc.
Also, don't forget a Myki. This almost happened to a classmate last year, and your teacher's not going to stick up for you if an inspector's there.