Just some tips I can give on colouring in different ways :)
First you should open up a new layer, and do a loose sketch, in BLACK.
Then you should lock the alpha of the lineart layer and get a bright colour (i used red ^_^), and use a big solid brush and brush over the lines.
You do this so you can see the sketch from the lineart when you start doing it. Itss just less confusing :)
Open up a new layer, unlock the alpha and draw you lineart in black at 1 pixel pencil.
You can see the differences i made, changed her head and stuff. you cna turn up or lower the opacity of the red lineart layer if it helps when you are drawing :)
This is the finished line art, and i made the background layer darker, because i find it less bright for my eyes :)
Now open up a new layer and use a solid brush (high opacity) and block in the colour of each item. NOTE: all these layers should be UNDER the lineart layer.
These are all the 10 layers i used :) I ended up grouping them by colour :)
Now on a new layer above them all i added one showing myself where my light source is. blue=shadow
NOTE: there is a reflective light towards her back on the blue dress, see it?
On her dress is gold, so its shiney, so its important to know where the light is cooming from. see the large shadow her shield is casting?
So now I made a layer UNDER the blue dress layer, in its shape, of just black and white shading.
So then i change the blue dress layer to multiply, and voilla! you can see the blue is shaded by the black and white layer! magic ^_^
Then you should MERGE the two layers and edit them, as the layer will be on normal.
I edited the staps by the way, because they looked wrong :P
Now the skin layer, get your palette of colours ready.. and block roughly the colours on the skin layer. NOTE: afer you have done this, you should lock the alpha on your skin layer so its easier to keep in the lines :)
Now in detail another way to colour..
lay down small block colours..
Now get the BLUR tool and blur it a bit..
Now your colours will be blurry, which doesnt look goos, as you need some blurry and some harsh lines. Most people make the mistake of leaving everything too blurry..
No add a bit of a lighter colour in the dark harsh line you put down..
So now when you have finished the foreground (cassandra in my case), so the bg next.
On the very BOTTOM layer draw your backgrond, add your signature on a layer at the very TOP also, and You are DONE!! :)
Yes I know my lines are messy.. but anyway! Hope this helps ^__^