Looking good man, I like your use of colour, I think #4 or 6 are my favourites.
If you're aiming for a more realistic rendition, it feels like your portraits could use a bit more structure and consistency. Your nose seems misaligned with your eyes in a couple of them - #1/2 are good examples I think, compared to a more accurate #6. I experienced this often myself :], and it's possible that you're moving. Maybe you're locking eyes with yourself after/before you draw your nose at an angle. I had to get really strict with my poses sometimes, and it can be really difficult to not end up drawing an exciting expression where my eyes looked 'dead'(focussing :p).
But, starting a drawing with planes, structure and proportional features will tie you down to keeping things unified. Your avatar image would be a great way to approach a self portrait. I'd like to see that ;]!