I find the best way to stretch out pizza dough is to work on a floured surface and handle it the least as possible without letting your hands get sticky. I like to push my fingers tips down into the dough and push it out into a circle. Then, pick up the dough by the edge with my fingertips and allow it to hang a bit to stretch out, then begin to turn it in the air to allow it to stretch on all sides. Place it back on the floured circle and make sure it looks nice and circular for toppings.