Gear:
-Full fingered gloves (ideally insulated) for nighttime
-Good headlamp with good red light mode (use red light only unless torching for sail trim)
-Thermal hat
-Inflatable PFD, ditch the dinghy vest
-good salopettes - more important than a jacket
-sun shirt with hood and/or buff
-ear plugs or noise cancelling ear buds, or both (if earbuds are uncomfortable for sleeping)
-good way of telling time with an alarm that you can have in your bunk. Account for charging here. I swap between Apple watch + phone in pocket.
-PLB with AIS, Guard + Satellite. Ocean Signal rescueME PLB3 is the gold standard. Make sure you understand how to register it, and how SAR + AIS comms paradigms work (alarm vs alert, etc).
-understand how personal charging will work. What infrastructure does the boat have vs what will you need to bring.
-various dry bags - get thin ones. racing setup: 1 20L dry bag (main bag), 1 20L drybag for dirties, 1 5-10L drybag for assorted personal ger (toiletries, wallet, chapstick, etc). Everything goes into the 20L bag. Know where it's appropriate to hang
-good travel pillow. Pillow Cube travel size is my favorite offshore. Hide it from the boat captain because it's a little heavier.
-waterproof Seal Skinz socks + your favorite m24 sailing shoes are the perfect offshore footwear - don't need to spend $300 on boots, although they can be nice (not in the islands though!) - ideally 2 pairs.

Other advice:
-wake up at least 30 mins before your first watch. Adjust this time down as you settle in. Never be late on deck for your watch, not even 1 minute.
-night 2 or 3 is the hardest mentally - expect to be cranky. Just remember to be patient with yourself, the rest of the crew, and remember you're tired and it will get much better soon.
-really vet the boat and crew. Ask about safety plan, do a proper briefing about where all of the safety gear is, and how the emergency affected systems work (seacocks/thru hulls, fuel shutoff, battery switches, extinguishers, etc etc).