Hmm I guess the Chav thing is a UK thing haha.
Basically a chav wears mostly football related brands such as adias, umbro and such, use slang like "init", "bruv", "blud" so terrible use of language really.
From your workspace I can see a picture of Salema Gomez. I believe she's actually 17.

Your newest face looks much better in my opinion, but I think the hair could be defined in it's curls and locks a bit more maybe so we can see where the hairs direction is instead of it being a pure blob? If you catch my drift.
I think you're focusing to much opun the left eye shadow / lins be the left of her nose that's next to her eye, in the picture of Taylor Swift she has shadow on her right part of her nose and not her left.
The cheekbone has been much improved as have the lips.
She looks much younger now then once you started.
And the bacon... Mmmm. Yummy!
As you can see in the picture also in Taylor swift she is using blusher (I think that's what it's called to make the cheeks rosey) Maybe you should adding a bit of pinkish red towards her cheeks.
That's a nice edit though Mathias.

Okay so this is my first constructive post, let's hope I don't sound like an ass nor offend you.

I'm 17 years of age and hang round with quite a few girls aged 16-21. So I should technically know.. Well kind of.
Where to start, with the underneath of her lips it seems to be as if it's being dented inwards, most girls I've hung round with and or have seen don't really have a big indent as that. I'm not sure of the perspective view either, not sure if she's tilting her head down or not. Do you have any picture refferences?
I think they could be of good use to you.

Her eyebrows go to far down, most girls I've seen around my age have small and not so bushy nor dark eyebrows, so try to lighten it up a little maybe? And make it shorter instead of so long. Not sure if you understand what I mean.

Her hair is no how a 17ish year old would really have it, although it really does depend on the teenagers style, Scene, gothic, Chav, Skater ect. Once you figure out what kind of style you want to persue research it througholy.
Scene teenagers would have big and poofy hair with bright and attractive hair, well most of them do anyway.
Gothic, well usually it's straight and black or really dark brown.
Chav, usually short bob, Erm. Like what I mean by bob is like long fringe kind of like Rhiana. Not sure how to spell her name but she has a bob a few times where it's really short but same length from her neck to her fringe? Not sure if I described that well enough or not. Possibilty of just a ponytail or even curly fringe layers and rest of the hair is straight but goes over the shoulders.
Skater chicks from what I've seen in my town wear hat suchs as "beanies" and "flatpeaks" as well do the chavs but the skater chicks usually have straight and quite long hair.
Maybe me telling you what I see as a 17 year old may of be some use.

Your image of the girl also has quite large cheek bones, I'd cut them down a bit to maybe something more softer? Like roundish dependant of the weight of that teenager.
Look for popular female singers like Rhiana, Jessie J, Taylor Swift. Those are artists but try to portray the age of teenager. If you're going for the Scene, Emo look then try looking for The Pretty Wreckless, I'm not suere of the lead singers name but she has a youngface.

The nose seems a bit to wide but that's just my speculation.
Sorry for the wall of text, I just hope this helps you somehow.

So after a few days of still trying to alter the base I can't get it to look anything like an elf.
Here is what I've got. 1st attempt is me altering my original base to try to fit it a bit more, 2nd one is a clean copy and paste of progFX's head onto one of green ravens templates because I wanted to achieve the big hands, 3rd one is a stretched and a few alterations to green ravens base.

I know I shouldn't really just be modifying people's template but I think the last looks okay-ish with it.
I don't know how to make a good base, I've tried redrawing the head and decided that maybe progFX's design is a similar way I should go, for now progFX's head is just a temporary place holder.
Oh also the elf I want to persue for the looks are the Lopear Elfs.
Some help would really be appreshiated in what I should do to improve and create it to my own base.

I'm having some serious trouble with the anatomy of things which makes my pixel art worse then what it should be.
I've tried making a elf base from using the refference I have given.
But obiously it's feet are terrible and whenever I try to change them they look even worse. The arms and the tummy off the base I have improved from what I could but it still just doesn't look right. I've tried lowering the arms, marking them higher, wider and smaller but still it just doesn't look good.
The tummy was far to fat and is still a bit to fat for my liking but I just can't get it to work with the arms and hands.
I can't pixel hands nor feet sadly and because of this I have hit a rock in my path.
Here's what I've got:

I've used the head from the dark elf because it seems to fit but I do plan on altering it.
I have no added colour to it because I feel it's lacking in a good outline.
What I'd like to use this base for is not just for a elf base but able to change the heads on the base to fit multiple races with a few modifications.
Sadly in the refence there was no real base so I shrunk it, took the colour out and this is what I got. I altered the arms to make it a bit better. But some help on this base would be greatly appreshiated to help me get in the right direction instead of being stuck.
Refference:

Hello Chaos Tayoko, I've added you on msn so we may speak because I'd like to contact you regarding GUI work.
Not sure if you log into msn or actually use it for e-mails. So if you could pm me or reply here to as if you do or not that would be great.
I look forward to hearing from you.