First:
Your heads are incredibly inhuman, and very bean-shaped. There is almost no definition to them. Ontop of that, they're far to tall, and their faces and bodies are un-proportional with their overly tall, skinny, beanshaped heads.
Second:
Their necks are too big, going back to the un-proportional nature of the artwork. Your necks extend all the way out to the end of the jaw, almost-- and it shouldn't be. If you haven't taken an anatomy class and have the ability to, then do so. It'll help your understanding of the body and your ability to draw it will improve. As well, if you arent taking an artclass, do so. Immediately. It'll help you in ways that you'd never imagine by testing and stretching your abilities while taking you out of your zone of comfort. Without art classes I'd still be just outside of stick figures.
Third:
Your foreheads are much too large and your faces are much too low. You give far too much room for the forehead- while important, the forehead should be shorter unless that individual has a much larger forehead then the norm. You dont start your facial features high enough, leading to low-set eyes, low (and cramped, atleast in that Lilian picture you posted) cheekbones, small chins, and lower hanging noses, resulting in your noses and mouths being right atop one another. (while this does happen, and often enough to be considered normal, not every person is the same proportionally in the face, and the majority of peoples noses and mouths arent that incredibly low, causing them to have no chin.
Fourth:
You need to isolate what it is that makes your style; what you like about it, what you don't, factor in criticism, and then start looking at other styles and figuring out what to adopt, what to keep, etc. That is the easiest way to change your style. Also the most productive. As well as that, look at your current creative process. What do you draw first? And do you draw an outline, or just jump right into the final product? I recommend making a skeleton first, like even just a simple head-shape and stick-body outline on a separate layer than your original- and also with an opacity lower than that of your going-to-be final product, like somewhere in the 50-60% range. Like this:
and here she is with as far as I've gotten (with all the various changes I've had to make along the way):
This method takes a tad longer, but it ends up looking much better.
Fifth:
You're trying to add in far too much extra detail to define things for your current skill level. You have to know your own limits, and break them in steps, not all at once. For example, the detail in the neck and on the chin in the Lilian picture. You could do without that extra detail for now because it detracts more than adds, as it distracts from the core picture itself by adding more things you have to shade, and since your current shading method- using the blur/smudge/water tool (or even the burn and blur, not quite sure which) creates unfavorable results, you should either just do flats or make as few things you need to shade as possible. The current detailing style you have doesn't look well to begin with, as its either thick lines or no lines at all, relying entirely on the smudging/darkening/whatever tool you're using to do your shading to create effects. Its jarring. Detail isn't meant to detract and distract from the original piece, but rather to add to and accent it. If there's too much detail in a small area or too distracting of detail, then you're going to take away from the original image itself.
Sixth:
The hair. Your hair has almost no shape or volume to it. Its so paper thin that they might as well be bald, as the hair itself is just a distraction from the face and head-shape, and while they are flawed as well, the hair is a
bad distraction. If you're not going to draw hyper realistic hair, which you probably don't want to, look into a more anime/cartoon style of hair. Its well volume-ized, it looks nice, and so long as you keep it proportional to the head, it can look absolutely fantastic.
Seventh:
Those eyes. They're trying to be like real eyes, but you currently either lack the skill or ability (physically, not in terms of preformance, just due to your set-up) to do real eyes, with all the important detail that makes that style of eye actually look good. The result of these psuedo-realistic eyes is a set of cold, piercing lemon eyes. Creepy as hell. You might also try a more cartoony, but still semi-real looking and rather nice looking eye-style. Look at, for example, Ravenwolfthorn or Ryciera's avatars for a female example of that. Looks nice, its rather simple, but at the same time, sort of a hard style to truly get down- especially with starting out. I'll tack eyebrows here too: They're too damn thick. Thick and almost taped-on looking. You need to downsize them by a lot. I seriously recommend just devoting a few hours-- even a day-- to studying other peoples drawing styles and seeing what you can take from them. Eyebrows are much harder to explain for me, so I cant offer much in the way of telling you how to fix it. Just know they'r too thick.
Eighth:
When you're coloring, you're not getting it all. There are still white spots all over the picture if you're looking at it in full view. If its far away, you cant tell. But once you expand it to full view, its jarring. Absolutely abysmally jarring. It looks plain lazy. Its an honest mistake to make sometimes, but you've made that very mistake
consistently. Seriously, if you dont believe me go back and look. As well, and many people have said this:
Don't shade with the blur tool! It doesnt look good! If you're going to shade, just do simple darker color tones of the same color applied in different areas the way you would see on a skin. It takes a bit longer that way, but it looks really good. The blur style shading is something some professionals I've seen cant even make good use out of. Its unfavored because its messy and blurs up your entire picture. Its different from a shading stump on traditional media. Significantly
so. Rather than a stumpy's method of taking the currently placed graphite and spreading it more through friction, filling in patches in the paper that might not have been entirely colored before because of the texture, and also smoothing out the effected area; the blur tool just blurs everything. It doesnt smooth it at all. It smudges it. Makes the picture muddy.
Ninth and final:
Use different layers! You've gone digital, mate! Use the damn things! Makes life as an artist so much better. If the program you're using doesnt offer them, you can literally download Photoshop CS2 for free from adobes website (if you want I can send you the link with instructions, its a tad complicated, but its from adobe themselves and its not a trial)
You can tell you arent using different layers just because your blur tool not only blurs color but also your lines. Its obvious. Layers lead to smother, cleaner final products. Its important to digital art.
Also, if you've yet to purchase a tablet and are serious on any level about this, then get one. Mouse artwork just doesnt turn out the same in the end unless you're truly truly gifted.