When you nuke your clay in the microwave, put it in a bowl of water. The water will evenly distribute the heat so you don't get hotspots. Also, if you go to take the submerged clay out of the water and burn yourself, its better to have a hot water burn than a clay burn, which sticks to your skin and is quite unpleasant.
But you really just have to warm the clay slightly to make it much more pliable. (Chavant NPS- medium)