I suppose I may as well chip in, as there is something bugging me about the direction of the thread and crits here.
BUT FIRST - welcome
this community has been a huge boon to me personally, and I know that I can attribute much of my development and success as an artist over the last few months to the feedback and inspiration I've found here. I hope that you find the same opportunities!
NOW on to business...this thread seems to focus on how these character portraits differ from traditional Pixel Art, which is a practice derived from developing games and software for mostly old hardware (but some new - DS, PSP, GBA, and mobile phones) - and thus has some kinda crazy rules about how many colors you can use, etc. For me and many other members practicing these strict color restrictions is just pragmatic as we have to use these skills every day developing new games. For others its a little more esoteric but no less important...
HOWEVER!
The main problem with your character portraits is not that they violate color restrictions, or any such arbitrary rules that may be specific to the realm of "true" pixel art (whatever that may be).
The main issue is that your grasp of color and form is weak and/or non-existent, irregardless of Pixel Art's specific rules. Every single character is pillowshaded in straight monochromatic ramps; regardless of what tools you decide to use, or even what software (or IF you are using software) this is a really bad idea if you want your results to look good. The renaissance masters did not use the gradient tool or the airbrush tool, and its not just because they didn't have it. These are special purpose tools that are designed for the manipulation of an existing, photoreal surface, or for simple graphic design purposes. Painters use paintbrushes. Just like they always have, and just like they always will! Our paintbrush just happens to say "wacom" on the side. No matter if you are painting in photoshop or pro motion or graphics gale, and no matter if you are even doing pixel art, your work will look noobish unless you understand color and form and light and shadow and you paint it to look like it should!
The fact that ptoing's edit has 16 colors instead of 130, while notable, is not the point of his edit (or at least it shouldn't be). Pay attention to what he DID with those 16 colors! Notice the clear light source - the varied, lifelike hues - the accurate shading and crisp, clear details. The only reason he did that with 16 colors was to exaggerate these points. Getting a perfectly smooth gradient across your surface is useless if it doesn't communicate anything about the form you are rendering!
Prometheus says it better (or at least more efficiently) than anyone I think:
http://www.itchstudios.com/psg/art_tut.htmRe-read it every night before bed. There are very few times in your life where you'll be able to improve just by reading something; especially something short. However, this is one of those times!
I hope that you are taking all these posts as encouragement, rather than discouragement - it is rare for a new member to receive so much attention, at least since I've been around
it means you have a lot of potential - welcome to pixel art!