I'll just throw the whole thing in here, suggestions are welcome, I was planning on doing some body hair, but right now I am not on best terms with hair
hehe
Also don't mind the background, I got so tired of painting on a grey background I had to do something hehe.
*snip of hunky Cullen*
Oh, my... The six-pack took me by surprise
I stopped scrolling down at the neckline, to study the features, and for some reason I did not think that there was more to the drawing than that (my brain is mush after 7 hrs of grant-writing). And then... yeah.. I get nice abs
Awesome 
The drawing looks really great so far. It's good that you are starting out with lighter colours - this will give you much better control over the shadows. A quick note on choosing colours: if your lights are cold (green, blue, bluish violet), your shadows should be warm (rich, dark red, brown, reddish violet). This will make things pop
Don't be afraid of saturated colours.
Also, to help you keep track of the tones in your drawing, it helps to desaturate the image from time to time (just add a desaturate layer in PS on top of everything, and turn it on and off to check things). This will make sure that your image is not flat, and you are taking full advantage of light and shadow contrasts 
PS: I am glad you like the stuff I posted, and hope that they can help you improve your own art 