As Gil mentioned, Proko pretty much covers everything that you need.
I wouldn't spend a lot of time looking for that magical book or quick 12 step program because it
doesn't exist.
(I'm looking at you thread in the general section)If you can't tell from peoples responses in this thread, paper-pencil drawing is really the only way to go.(maybe tablet if you are comfortable enough)
Also to be completely honest, your pixel person is pretty terrible. Somehow I doubt you'd do worse if you translated that to paper and pencil.
Seriously, you need to drop your misgivings and just jump right in. Use Proko for guidance, start your own practice/studies from there, I guarantee in even just a week you'll notice an improvement.
At the end it all comes down to practice practice practice