This example can give you a good idea of the style i talked about.
I finally began studying some photographies, and here is my first attempt at making some serious realistic digital art! Ever since i began drawing, i never tried copying stuff and never used references in my works, because i got bored quickly and couldn't bring myself to copy anything: i just wanted to invent stuff rather than copying it.

But now things have changed, as my new goal is to be able to create realism from my imagination, so that i can use it to improve my comic, and this new goal gave me the mental strength to finally be able to actually copy something and study it!
Needless to say, i learned more by drawing this eye than i ever did by reading books on the subject.
Just as i thought, copying (which means studying) can be a great help, because a book can teach you only so many things, the rest depends on your observation and studies!

I also think this will be a great help because i can finally make use of my quite decent photographic memory:
my plan is to copy as many photos as i can, so that over time i will learn the principles behind these/ memorize the process of drawing various parts and be able to create realism from imagination.

So expect more of these studies: my commitment to drawing is now at its peak, i'm making the final leap and i will begin studying realism and studying drawing harder than ever!
And yes, that means also copying stuff to learn much quicker than by randomly doodling imagined stuff. :)

This one took about 30 mins, i hope i'll get faster as i keep doing these and as i get used to these realism techniques!
I'm not that satisfied with this first study becuase i changed too many things and couldn't reproduce it exactly as it is, but i'm glad that i could finally bring myself to start copying photos and i feel like i already learned a great deal more about a realistic eye, and i'll soon switch to colors!