Bring plenty of water and sunscreen. To get to the green sand beach from the parking lot there are locals that will drive you there for a fee. If you decide to walk there are no signs to direct you which way to go.
We stayed on the dirt path and looked for the vehicle that were transporting people to the beach.
The beach is beautiful and probably the best maintained in Phuket BUT you have to pay to enter! No outside food & beverage allowed, security watches visitors all the time and it's really creepy at some point.