If you want the dough to be strong and stretchable before baking it:
What works best for me is to use a high-gluten flour (such as bread flour, and sometimes I even add more gluten) and to knead the heck out of the dough. That builds a very solid gluten structure that can pass the windowpane test.
If you want the final, baked crust to be softer or "springy" and more bendable:
You probably want bubbles in the dough. To do this, make a yeast dough and let it rise for a little while before baking (as opposed to quickbread, using baking powder or baking soda to make bubbles). Knead the dough a lot. Adding too much oil can cause the crust to "fry" in its own juices, but you want enough to keep it moist. One thing I do is I partially bake the crust before putting on toppings (about 5 minutes -- just to make it a little firm). Then I add the toppings. If you wanted the crust to be softer, put a little oil or butter on the outsides of the crust (the edges and even the bottom, but not where the sauce will be). This will help keep it from drying out. You could also try baking the dough at a lower temperature to make it more like a bread and less like a cracker -- but you'd have to experiment with this.
As for kneading the dough: knead it a lot, but let it rise. Then you can use a rolling pin to keep it flat. Bubbles aren't bad -- small bubbles can help your dough bend.