Where can I find modeling exercises?

When I try to create a model I always end up with too much edges and millions of triangles and unwanted spikes. When I watch others workflow I see clean models, as if they know beforehand which cut or subdivision to do. Where can I find exercises just for this subject, like making a basic to complex exercise or something like that?
BTW the Wiki is being hard to understand about this…

What is it you are having a hard time with in the wiki?
Here is a great site for some video tutorials: CG Cookie.
This face tutorial should give you some ideas on how to plan out edge loops and maybe how to start the modeling process. Here is an animated gif that goes with that face tutorial.