I don't think tessellations is the right word - that applies to repeating/tiling patterns like m c escher's reptiles

But if you are asking, "How do I simplify a rounded object into a sculpture made out of triangles?", I can try to answer that. Most living things and many human-made ones have rounded shapes. The natural way to convert them into a 3D model is with NURBS. (3D vector curves or bezier curves). But if you want to use triangles, then you have to mentally convert a rounded shape to one made out of triangles. Cone shapes are the easiest - those are pyramids, though you can vary the number of sides as desired. Tube-shapes are like if you took a right-side-up cone and an upside-down cone, opened them at the seams, then interleaved them: they are made of tall skinny triangles alternately pointing up and down, sharing their long sides. This also works for a tube that tapers from one end to the other. If you want a bulge in the middle of your tube, you split it into two tubes, such that they both taper to be widest at the bulge. If you are modeling anything symmetrical you typically only model half and then let the 3D program automatically mirror that half to complete the model. So typically the center line of the finished object will be all triangle edges, no faces. Near-spherical parts of the model are going to be a geodesic dome. Over all, you want to minimize the difference in angle between any triangle and its neighbor (unless you want a sharp corner or edge in a model at a specific place.)

there is no right or wrong beyond the following simple principle 'if it looks right, it is right'

its unlikely you have polygon limits to worry about so its down to will the mesh do what it needs to. edges tend to need to compliment the movement and the silhouette.

Noses were always a real ball ache on PSone games. huge chunk of the poly budget for a nose and heaven forbid they has to have anything but a fist