A friend of mine made the sketch i just added some details and colored it so i do not own this.
My friends DiviantArt http://algrajh.deviantart.com/
You may want to try using a heavier paper. If you can get a hold of some smooth bristol board there won't be as much of a chance of the texture of the paper showing up through the coloring. Also consider coloring a bit lighter at first and then add layers where the darker areas will be. Here's a good example of what I'm talking about:
http://www.furaffinity.net/view/11580600/
You can see where he started off light and slowly darkened where the areas of shadow are.
Hope this helps :)
Link
freder
What type of paper are you using for this?