The beach is 5 kms away from the Tulum town center, so your mode of getting around matters. Although this does not sound like a long distance, once you get in the open tropical sun you realize that distances can be relative.
Highly recommendable and very popular. Getting around town, to the beach and the Tulum ruins is easy and fun on a bike. It might feel and look a bit risky because of the sometimes crazy traffic, but accidents are very, very rare. There are numerous bike rental services in Tulum. Pricing could be from 80 up to 200 pesos per day. Some of the bike shops provide assistance in case of failures which could be quite handy in case of a flat tire or broken chain.
This is another popular option. Especially in the summer months when cycling is inevitably sweaty experience. There are only a couple of places where you can rent on the beach strip. Some of the better rentals shops in town deliver motos and bikes to the hotels at the beach. You can only get as far on a scooter though. Riding a scooter on HWY 307 is possible but not really fun experience. Rental rates vary from 450 to 700 pesos per day.
Taxis have no meters in Tulum. Instead, they have a tariff list. Of course, if you do not know the tariff list by heart, you are always subject to manipulation. Taxi drivers are not famous for being the most honest or compassionate members in the Mexican society. So be aware. Ideally, you should know how much you have to pay to your destination. For longer distances, you can often negotiate a better price directly with the driver instead of going through your receptionist or concierge.
If you like to drive and you are planning to explore more, then renting a car could be a very good option. Moving around town or the beach strip in a car is a drag, though. Parking, especially on the beach strip, could be difficult to find and costly. In the same time, some of the cenotes and nice archeological sites are a bit of a distance away so a car could be quite handy. There are a number of car rental companies in Tulum. Prices vary according to the time of the year and season by season.
The shared van service collectivo is widely popular in the Riviera Maya. Especially among the locals. It is the most inexpensive way to move around. There are regular services from Tulum to Playa Del Carmen. It can be used to get to Tulum ruins or some of the cenotes.
Very convenient for longer distances. There are regular services to Cancun Airport, Coba and Chichen-itza along with some other interstate destinations. Best way to get tickets is in advance at the Bus station in the center of Tulum town. Timetables can be checked at their website.