Upon entering Pura Uluwatu (even if it's the surroundings of it), you will need to put on a "sarong" (a piece of material wrapped around your waist) and tie a sash if you are either not in long pants or in skirts. For those who are in long pants, you will only need to put on a sash. These are provided at the entrance and the fee is already included in the tickets you purchased. This is not only a custom in Uluwatu - it is a custom in Bali whenever you enter into the vicinity of the "pura" , temple.
If you are near to the souvenir cum drink shop next to the white cliff viewing point, you will see the interesting green mat which the local used to sit down, which is actually made from the long leaves of the surrounding plants. Very interesting and unique indeed :)
The temple at Uluwatu is out of bounds to visitors and we can only see it from the outside. There are signs which say that the temple inner grounds are meant for devotees only, so do not enter as a mark of respect.
If you are wearing shorts, you will be asked to wear a cloth around your waist before visiting the temple as shown in the photograph. This is a mark of respect for Hinduism.