Both species eat a most types of bait, but Pilchard and Squid are safe options and are readily available. Fresh Kahawai fillet is a excellent Snapper bait. Fish can be fussy at times, and would only take a certain type of baits so Its a good idea to bring and use more then one type.
Squid is a very under-rated bait. I have caught just about everything on squid including snapper and elephant fish. The best idea it to take two or three baits with you and try them all.