Why do you want to learn to tread water? Before you can tread water you should be able to swim. There is no best technique but how comfortable you are with your arms and legs.
As far as I know, there's no such thing as the best technique to thread water; there's only one technique. It's keep your head above water with your body in vertical position and your limbs doing scaled down breaststrokes, scaled down just enough to keep your head above water.
There's another technique but it's not technically threading water. It's just floating and flowing with the water. Keep your face up above the water in a backstroke position without the strokes, just enough waddle to keep your body afloat and face above the water.
There is a technique, to keep afloat you have to learn breast stroke. You kick in the water with your feet and then with your hands. Do not do both actions at the same time, it's tiring and is the wrong way of keeping afloat though it seems logical.
Lastly, relax yourself and don't panic... keep practicing and you will succeed.