Following up on Kari's suggestion...If I have not already lined up a tour guide through the internet, I will ask the taxi drivers some questions before I hire them. Money of course, along with time involved are important, but I also follow up with the question of what he/she will show us during the time. I make sure that I can understand and communicate with them and that we will be the only customers. In the hot climates I also make sure that the taxi is airconditioned. I verify in advance if there have been difficulty with taxi drivers and if there is a difference in licensing.
My wife and I will be going to Cozumel twice in March. The first trip with grandaughters and the second with grandsons. Ages 10 - 14. After you return I would appreciate any suggestions that you may have.