Dunno if the category is right, since this is more of a how to, than a tutorial, but well, i wanted to do one of these ages ago, but SAI crashes if the file is too big, it nearly crashed when making this too, but i managed XD.

STEPS

1-Pose sketch: Here i just do a very quick, very ugly sketch of the pose i want, as you can see, it sucks XD.
2-Base design sketch: Here i sketch the design of what i want, clothes, hair, face and a rough draft of the details and stuff.
3-Lineart: Here i do the clean lines, the lineart, and i add the things i see fit and change what i didn't like, for example, she had short hair in the sketch, and i decided i wanted a ponytail better, and i changed the face since the other one didn't look okay to me.
4-Base colors: Here i just color each area on a new layer, i decided the colors i want and play with the filters a bit until i get something that looks good to me.
5-Skin airbrush: Very simple step, i choose a darker color than the skin (not much) and airbrush the zones where the shadow is stronger.
6-Skin shading: I do a layer on multiply and with a reddish/skin color i shade where the shadows go, and i blur some areas with the blur or water tool.
7-Skin shine: I create a new layer underneath all and put some white where the light shines and blur it, then i add some little details like a blush on a new layer over all on multiply, and add some withe dots for cutesy.
8-Eyes shade 1: I shade the eyes with a darker color and blur a little.
9-Eyes shade 2: Same as step 8, but with a darker color.
10-Eyes shade 3: On top i create a new layer, make the pupil, and shade the top a bit, i add some lighter dots as well.
11-Eyes shine: I create a new layer underneath all and on luminosity i color and blur.
12-Airbrush hair: Airbrushing on the darker areas, then blur.
13-Hair shade: Shading the hair following thr flow and the light source.
14-Hair shine 1: Here i make a layer on luminosity underneath all and shade some zones.
15-Highlights: Here i shade the hair nearest to the light source with clear strokes.
16-Highlights 2: Here i just add some dots and lower the opacity until i like it.
17-Ruffles shading: Here i shade the ruffles and blur a bit.
18-Overlay layer:Here i create a new layer, with purple color, and put it on overlay, then lower the opaticy to give it a purpleish shade.
19-Dress airbrush: As always, airbrush the darker zones, then blur.
20-Dress shading: Layer on multiply, shade the dress.
21-Dress shine: On a layer underneath i lay some lighter color and blur it, then add some details with a more lighter color.
22-Gold shade + shine: Just shading the golden parts, jewelry, stars, etc.
23-Accesories:Shading the accesories and adding some shine too.
24-Added white on the eyes and a bit of luminosity.
25-BG1: I added a totally black bg, then added the water texture.
26-BG2:I added some different purple colors, blurred them, then added a texture.
27-BG3:Added some white dots for the lulz.
28-BG4:Colored with dark purple a path, then added a texture to it.
29-BG5:Same as step 28, but i did it on luminosity and just underneath her, blurred the edges.
30-BG6:Same as 29.
31-BG7:Created a light source on luminosity, adding a new layer to make it shine more on the inside, used 3 layers.
32-End: Here i drew some (shitty) mist, as well as a border on her and the BG, and it's the finished piece, all in all, it took me, a whole evening + 5 hours or so from the day when i did the lineart, hope you enjoyed this!!<3

Art, tutorial (c) Me, do not redistribute.

Textures~excaliboob