Any recommendations/advice would be greatly appreciated (e.g., dive shops, dive sites, things to avoid, etc.). This is my first time diving in Mexico, and my first time in Cozumel, so I'm pretty excited.
Well, there's the usual...
Take a pen on the plane to fill out paperwork they disperse before landing. Keep the stub you get back from Immigration safely with your passport. You are supposed to carry both if you go into town or on the ferry, but at least don't lose them. I keep a copy of my passport page with a spare PP-pic with my paperwork separately just in case.
Avoid the lying timeshare hawks that try to cut you off as you leave Customs. Just get a van ticket to your hotel, make a headcall, buy a beer and get on the van.
Got DAN dive insurance - not the cheapest, a safety sausage and other signaling devices?
Lots of good Ops to chose from. Just read over threads for a couple of pages and email some. Whoever you dive with can help you with buddies or you can buddy with the DM. Got all of your own gear? There's a lot to be said for the convenience of diving with the hotel's Op, especially if you need to rent gear.
As new as you are it would be money well spent to hire a private DM the first day. All of the sites are good as DMs depend on tips so they make sure you are happy. Maybe $5/tank and up, some tip much more, and the DM shares with the captain.
Take lots of $1s, $5s, $10s and I get $2 bills from my bank and tip the folks who are nice about making your stay fun: maid, waiters, porters, etc. No torn or marked bills.
Taking a laptop? Skype is the best way to call home. If you subscribe to the $3/month plan to call US and Canada from the US, then you can call home for free - and cancel when you get back if you want to. Take a headset. I forgot once but the headset from the plane worked.
Get out and see the island. Maybe make friends and hire a taxi to drive around the south end one afternoon, making stops, dinner in town. Renting a car comes with cautions; renting a scooter is dangerous.
Take a digital luggage scale for packing and get back to the airport early. Winter travel is always an adventure.
Have a good trip. ilot: