Ms.Grumpy Gills

Hahahah Wow this looks amazing, your best artwork yet <img class="avatar" src="a.deviantart.net/avatars/m/o/m…" alt="" title="monkeythumbplz" />
The style in which it is drawn is incredible :]
At the moment, I would say that something like this would be worth 20-25 pounds

But there are a few things you could to do make it better [and worth more money] xD

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The easiest of which would be adding a background which is not just a solid colour, and making the background more....a part of the piece...
Just something as simple as adding a cast shadow underneath her would make it look better. You can also make the background a radial gradient too, so going from 50% black on the outside to around 20% black on the inside. Adding a subtle texture on top of the gradient also adds interest. [but it would need to be very hidden; the viewer should not notice it there.
That, if done right, can make it worth an extra 10 pounds.

Also, I am not sure if Lozzy has scales..........but I assume that she has small ones like fishes scales.
To make scales show without painting scales, in the most illuminated areas in a colour very close to white, use a speckle brush to paint.
One that should work well is the soft skin brush from DanLuVisiArt's brushes.
It might also help it look better if you make the bounce lighting a bit more.....extreme xD

Also the feathers might look better if you added short loose strands at the bottom :]
also maybe desaturate the colour as it gets lighter

Also
uhhhhhhhh
For her wings, are those supposed to be folds?
[hahahahah if they are I'll edit in what i was gonna say]

Also, on the back wing why is there no bone part at the edge?
And why does the floppy membrane part of it not meet the edge of the bone part on the front wing, like this sta.sh/09tzdbcw59i


Aside from that, It is a perfect artwork :]

also your signature looks like it says gairl-in-a-fez xD