If you've been following this board and practicing everything you should be a professional at drawing eyes by now. I saw yet another style and had to pin it. COMMENT HERE for anything specific you want to know how to draw, or any specific technique you want help mastering
How to shade & pencil shading techniques
Tutorial: How to Shade Learn shading techniques, tips and tricks for shading realistic portraits.
This could come in handy, I do have some difficulty drawing noses, but it has the circles first, which always sucks. :P
Lips. | 17 Diagrams That Will Help You Draw (Almost) Anything