When you start to throw at first all you want to do in consistently throw a straight cylinder with even wall thickness. The shape all the way to the right has a very even thickness while the the middle one has a more varying thickness. Wall thickness is important because if you make the wall too thin it will tear but too thick and you waste the clay. Once you can throw a good wall thickness every time you can go on to change the shape of the piece into whatever you want.
I'm still in the stages to working on the wall thickness as I still make the wall too thick. In the long run I would like to be able to get to level where I could work on pottery until it is good enough to sell.