
I recently completed this piece (the characters are from an anime called Code Geass, for those who are curious), and along the way I tried to make sure to save various degrees of progress.
Onto the first WIP (work-in-progress):

I prefer to start with linework drawn on cardstock, over most other papers (bristol board is ok, better for doing markerwork I think). I like the way that cardstock holds the pencil lines, nice and smooth - its also good for markers. The linework doesn't always have to be perfect, since I'm painting over it anyway. I can't draw very well on a tablet, but I can color just fine. Huh
For this piece, I didn't want to show all of Suzaku's face. I felt like it was more mysterious & less obvious not to - anyone who has watched the series knows who he is without seeing his face.

This image shows the base colors I put in. I almost always work from dark to light, and prefer to work on a purple-toned image.

I focus on painting the sky/background, and then characters' skin. I'll probably start on the clothes or hair next, once I am happy with them.

Here I start on the clothing - it is not something I like to paint without reference at ALL - but I tried my best! Can't improve if you don't try, right?
Unfortunately as I ramped up to finish the image, I forgot to take any more WIPs! Sigh! I did however shrink her head down a lot... it was waaay too big.
Here is an animation of the progress:

I hope that this was useful on some level... if you have any questions or helpful tips to share, please leave a comment~