For those of us not used to travel by boat, even the ferry ride was a fun experience.
From the Cancun airport you can either take a taxi or shuttle van to Puerto Juarez, just north of Cancun proper for the ferry ride to Isla Mujeres. There are many "helpers/porters" at the drop off that will gladly help you with your luggage from the taxi to the dock for a tip. You should be prepared after getting off the plane in Cancun with plenty of tip pesos or dollars.
There are a couple of options. The new ferry runs all day long on a regular schedule, and is just over $3 for one way fare. It is enclosed and a fast 15 minute trip over to Isla. The slower ferry has an open deck (sigh, I can feel the breeze now) and takes about 30 minutes to cross.
Once you get off in Isla, there again are bicycle carriers/porters that will help you with luggage to your hotel, or you can take a taxi. We enjoyed the walk through town with one of the bike guys who was friendly and had plenty of storage with the bike trailer.
A bonus to the ferry dock at Isla Mujeres is the woman who sells banana leaf wrapped tamales that are excellent (the red sauce and chili powder is a great addition if you like it hot). We tried these on our second trip and were glad we did.