Playa Del Carmen and Cozumel are especially notorious for fraud, copying, and the theft of credit cards. There are hundreds of credit card fraud stories on the Net about these two places.
Beware of waiters or hotel attendants "double swiping" cards, even at reputable places. Also be cautious of fake ATM machines, plain white machines that look innocent enough but don't actually dispense cash, they read "out of service" once you swipe your card. (I got taken in by one of these.)
Use cash for transactions whenever possible! In Playa, use the ScotiaBank across from the bus station, but cover your PIN number when you type it in and take a look around the machine for any hidden cameras that may have been added by thieves. If you must use your card, never let it out of your sight, go with the waiter or worker and watch everything they do. This is a huge problem in this area of Quintana Roo. When you get home, check your statement often (online or over the phone) to make sure nobody's currently using your numbers.
Be sure to look for the stamp .925 or .950 on the silver. It is especially good if there is the stamp Mexico or Mex with the numbers. There are a lot of fake silver vendors (usually they are walking along the beach). It is better to buy silver in a store than from a person walking on the beach. Although I did find a shop in Playa del Carmen that was selling fake silver to tourists, but most of the time the silver in shops is safer.
The respresentative from Best Day told us to be careful using our credit card in Mexico, he said that some unscrupulous people would write down the amount in pesos but if they didn't write pesos next to it, they would get paid in dollars. So a 600 peso charge which should be about $60US would show up as $600US. Make sure that pesos is written on the credit card slip before signing it.
Maybe it was the season....every niight at sundown, if we were on the beach, we were practically devoured by Mosquitos. the worst were at an Open air restaurant at Tank-Ha. which is a GREAT place to be during the day.
Take your own repellant! The citronella just didn't seem to cut it and by the time we got to one of the small drug stores that was all we were able to find. If you have time to shop in the H..UGE supermarket it Playa..Chederaui I'm sure you can get anything, but be prepared and pack some from home. I'm still itchy!!
Getting through the airport in Cancun can be a challenge for the uninitiated. Getting through passport control is quick and getting your luggage is quick. Passing through customs on this particular journey was lengthy, well over a 1/2 hour, but painless except for the thought that this line was all that was separating me from the warmth of the Mexican sun.
The fun part starts as you make your way through the gauntlet of taxi drivers, time share sellers, etc. that you encounter right after you pass by the final luggage check. If you are on a package tour with Apple, FunJet, Expedia, etc. or have prearranged a transfer with your hotel or a taxi service, ignore everyone inside the airport and make your way to the area outside that is just past the fence, this is where you will find the tour representatives or someone holding a sign with your name on it.
Beware of the time share salesmen. A lot of them have storefronts set up like travel agencies. When they mention that they will give you free tickets to whatever activity you are interested in, run as fast as you can!
I've never been sucked into one but I understand that they can last for hours and they are very high pressure. But some people, especially if they have a lot of time for vacation, actually plan on going on these while on vacation if they are down there for a couple of weeks to make a little extra money or get free excursions, just make sure you know what you are getting into.
Our resort this time, the Reef Playacar, even had one inside the resort, set up as a concierege, the minute she mentioned Royal Haciendas and said something about free tickets we politely excused ourselves and booked our excursion with the representative from Best Day Tours that Expedia uses.
I have never suffered from this particular ailment but I have known people that have become very ill in Mexico.
The basic rule to be followed it boil it, peel it, cook it or forget it. This isn't foolproof but it certainly can't hurt to make sure that the food is hot.
A couple of other tips:
drink bottled water-it's cheap and it's not worth the risk to drink the tap water
I read somewhere that you should take a Pepto Bismal tablet every morning as a precaution. I didn't do this in Mexico but I did in China.
Bring some Immodium with you.
There is no point in bringing your mobile to Mexico any more because their service providers really take advantage on long distance calls. I checked my rates the 2nd day I was there and they were going to charge me $3.50/minute, which is completely ridiculous, especially considering the fact that we are on the same continent (eg. from Tunisia it costs $1.50 to call Canada).
The National company selling Phone cards in Mexico will charge $1.50 to $2.00 USD a minute.
You are much better off going on the 5th avenue and going into one of the many phone stations which will charge 0.20 to 0.30 cents to calls made to the US and Canada. Calls made to Australia will cost about $1.20 USD. There was one with a really nice owner on the 5th and 14th avenues.
Literally everyone that provides you a service expects a tip from the bus guide coming from the airport to the bell boy to the tour guides to the snorkel trip operators and they are not shy about asking for them or telling you that tips are a big part of their income.
I think that it is true that tips are a large part of the salary for people in the service industry in Mexico so I gave them freely when I thought the service was good which was almost all of the time.
With the exception of liquid souvenirs like hot sauces, vanilla and tequila which you can't carry on a plane anymore, you'll want to buy your souvenirs in town where they are 2-3 times cheaper than at the airport plus you can sometimes barter in town if you are buying several things from the same store.