Sculling allows you to tread water with your hands. To scull, keep your hands outstretched to the side and completely submerged. With your palms facing toward one another, move your hands towards one another until they are almost touching. When you've reached this point, turn your palms facing outward and move your hands back out to their original position. Try to keep your hands doing one fluid movement back and forth.  The advantage: you can keep your legs free by sculling, allowing you to combine this with another foot treading technique such as the flutter kick. The disadvantage: you have to keep pretty much your whole body (minus your head) underwater. Also called the eggbeater, this is where you move one foot clockwise while moving the other foot counterclockwise. This technique is hard to master, but it saves a lot of energy.  The advantage: you save a lot of energy doing this technique if you can perfect it. The disadvantage: this is a hard technique to perfect, and many people need to practice extensively in order to learn it. Lay back in the water in the same manner as floating. Immediately move your hands in a circular motion. Move your feet up and down together.  The advantage: it's very simple to explain to children. The disadvantage: circling hands can become tiring.

TL;DR in Indonesian:
Cobalah gerakan mengayuh. Cobalah tendangan memutar. Cobalah teknik helikopter kecil.