What are some different ways to make tofu?

I have been a vegetarian for a while, and my sister just decided to help me make more vegetarian meals in our house. I really had never cooked with tofu before she started making dinners with me, but a lot of the dishes she wants to try have it in them. She tried to make Pad Thai the other night, and she cooked up everything and threw the tofu in at the end. it turned out really mushy and kind of gross. How can i cook tofu in future meals like this so that it isn't so mushy and bland?