Modeling a cow - Problem 1

The objective of this exercise is to model a cow, starting with the head. I have learnt basics of modeling in my previous IN3D module, but modeling a realistic object proves to be a difficult task.

I encountered many problems when I started to model the cow's head. When I got to its eye, I realized that there were multiple edges on a single edge, which caused severe problems when extruding. I tried to delete the edges but couldn't. (From the image, it can be seen that there are multiple edges present.)

Hence, I approached my tutor for help. He taught me how to open up a window where I could see the number of edges selected, as to determine the number of edges present. He also taught me to use the vertex merge function to merge the two vertex such that the edges would merge too. However, even after knowing the solution, I found out that the task will be quite tedious as I have many parts with the same problem and it will be difficult to correct all of them as the vertexes are all at the same spot. Hence, I have decided to redo the cow's head.

My tutor has also told me that careless extrusion might have caused my above problem, and so I will be more careful with extrusions in the future.