Hey man welcome aboard to the game of well.. yeah.
Right off the bet I can say you definitely have improved especially the way you draw the features, making something look believable and more real.
What I feel maybe (remember from what I am seeing so far) is you could up the level a notch by doing more finished portraits, as in, going from start to more finished look. There are a couple of articles that I could suggest you to read (for the more applicable things)
http://www.dorian-iten.com/articles/
I will not bombard with too many information, rather will just share a small bite-size for someone to check and apply in their own workflow. If by any chance you're interested in more resources later on, you can check the Resources Thread in the General Section.