Epiphany a.k.a I just realized I'm all over the place

So I've been drawing for a while, I'm not too bad but I'm kinda wandering here.
That is to say I want to improve but I'm at a lost what to zero in to REALLY improve.
I just posted on the 100 drawings challenge but I'm having trouble breaking down my issues.
I know I suck at perspective.
My drawing Faces is shabby.
Also my Shading needs work.

I need exercises and strict regime to practice.
Ideas?

I had great help from the book by Betty Edwards "Drawing on the right side of the brain" and a lot of practice, like years.

Thanks.