If you have never used subdivision surfaces before, the following workflow description will help you get started:

1. Create a polygon mesh that roughly captures the basic shape of the model you want to build. Ensure you initially construct it with a minimum amount of polygons as much as possible.

   This model will determine the base topology and control points of the subdivision surface when you convert it to a subdivision surface. Subdivision surfaces are very effective at creasing and refining edges so you don't need to put a lot of effort into capturing those types of features in the polygon mesh.

2. Select and object and press the 2 button to get an idea of how the rough polygon model will convert to a subdivision surface as you work on it.

   You can also convert to subdivision surface to check the conversion and then undo back to the polygon model.

3. After you convert the polygon mesh to a subdivision surface, adjust the shape of the subdivision surface by pushing and pulling vertices.
4. If you need more control in a particular region of the mesh, create a new subdivision level while working in Standard mode.
5. If you want to apply a sharp edge to a region of the surface you can apply either a full or partial crease.
6. Switch back to Polygon Proxy mode if you need to make topological changes to the surface (for example, splitting a face). You can use the polygon tools to edit the subdivision surface while working in Polygon Proxy mode.