Right now I'm using this forum primarily to ask questions.  So I thought it would be a good idea to "give back," and mention a couple of awesome modeling tips that other newbies might find useful.

1)  Hiding part of the mesh.  When I was confronted with the challenge of fitting a couple of eyeballs into a head, I realized that I needed to hide part of the mesh in order to be able to see the edges of the eyelids from the right angle.  Well, this is incredibly easy.  In edit mode just select the vertices you want to hide, and then hit the letter H!  To show all the mesh again, press Alt H.  To hide the de-selected vertices, press Shift H.

2)  Controlling the lighting for modeling.  The lights that illuminate the mesh for modeling are the Solid Open GL Lights.  They can be adjusted in the System & Open GL panel.  This panel is one of the tabs of the Info Window, and the instructions for opening it are here:  http://wiki.blender.org/index.php/Doc:Manual/Interface/Configuration .

Say for instance I want to look at something that is on the dark side of the mesh.  I just open the Info Window and adjust the GL lights so that the bottom side has some light on it.

Hope that was helpful...

#2 was new to me, I generally model in "solid" rather than shaded mode.  Hiding bits of a mesh is definitely handy for getting stuff out of the way and freeing up memory if your mesh is getting a little too huge.  If you're not using vertex groups for something else yet, you can use them for things you frequently find yourself hiding.

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1)  Hiding part of the mesh.  When I was confronted with the challenge of fitting a couple of eyeballs into a head, I realized that I needed to hide part of the mesh in order to be able to see the edges of the eyelids from the right angle.  Well, this is incredibly easy.  In edit mode just select the vertices you want to hide, and then hit the letter H!  To show all the mesh again, press Alt H.  To hide the de-selected vertices, press Shift H.

Alt - B works good as well  (At least for blender 2.49 and below) .  Alt - B, select the part of the 3D view you wish to isolate and the rest is hidden.  Hides everything outside of the selected area, other objects, lights, etc.    Alt-B again to restore the view.