This modeling tutorial shows how to examine a polygon mesh object that has problems and how to correct. It shows various techniques for figuring out what may be misbehaving in parts of the polygon mesh.
This materials and UV tutorial shows how to be aware of and work with the UVs of subdivided objects, especially when textures need to conform to the edge of an object.
This materials and rendering tutorial shows how to impart subtle surface shading for diffuse materials. Specifically, it shows how to use the fresnel interpolator to adjust the reflectance at glancing angles to help give a greater sense of dimension to diffuse shaded objects.