Hey man, nice work. You have a nice sense of value going on and your overall sense for colors is getting stronger. You might want to bring out some harder brushes and bring out those sharp accents here and there, though. Look up the old masters like Sargent, Velasquez (especially the later Velasquez was known for his incredibly broad vision - both tonally and in how he only left a few sharp accents in his carefully wrought out softnesss - to bring focus where it was essential), Rembrandt and Repin.
I think that getting back to basics a little, will help you in further solidifying your digital work. Spend some more time on your structure drawings and learn how to specify your line work, using straight lines. Opting for stright lines will give your works more specificity, and specificity brings along structure and solidity of form. It'll do you wonders!