I don't claim to be an expert in this by any means. If you're like me, and still on the new side of learning, I'm going to share the things that I think about as I colored this image. I hope it's helpful.
I started with her legs, since they are underneath the sheer skirt. Everything under the sheer fabric needs to be colored first. I used my lightest skin tone to give roundness to her leg and then added my darkest skin tone on the parts that are in shadow. Don't worry, I'll show you my color chart at the end.
Next I colored over the light areas with my medium skin tone.
To finish her legs, I blended with the lightest skin tone. I also colored in her shoes before moving to the next step - the dreaded sheer skirt.
Turns out the sheer fabric isn't as hard as you think it is, once you get over coloring over your already colored image (this always makes me nervous before I start). First, I looked for the areas where the fabric seemed to have multiple layers and colored these with my dark color and medium.
I blended these in with my lightest color. I wish that I had had a marker that was a little darker for the lightest shade, but you make do with what you have.
I did the same thing on both sleeves - coloring the arms first and then adding the shear sleeves. Sorry the pictures are a little blurry, I was trying to zoom in on the small area.
The next part of the image that I focused on was her dress. I love these images because the artist has given us lines to guide our coloring. I'm not great at unguided folds, but these lines make it a lot easier. I colored the skirt in sections adding colors dark to light. I started with this fold which is curved out toward us. I added the darkest color along the edges and then the medium color.
I added the light color to blend. Then added the darkest color into the folds on the right.
I added the medium and light colors on the right blending out from the darkest shade. Then I added the darkest shade to the areas on the left. You can see how I'm breaking down the skirt based on the drawn lines.
When I finished the vertical sections of the skirt, I moved on to the horizontal sections. For these ones at the top, I started with the dark color along the fold and then blended to light as I moved to the top. The fabric is folded over at the bottom, which is casting a shadow.
Here's the finished dress. I tried to zoom in so you could see where I put the shadow and highlights.
Finally, I needed to color her hair. I was going for a Celtic princess look so I chose red-browns for her hair. I started with the darkest color in the areas where her hair was layered or seemed to be recessed from the light.
Then I added the medium color blending out from the darkest color.
Finally, I added the lightest color.
Here's my color chart with all the colors and where I used them.
I had just seen Brave before I made this card. Probably inspired the Celtic princess. Here's my finished card: