Hello, welcome to Pixelation.
Using someone else's lineart as a base, and starting with lineart in general, are two habits you'll want to drop immediately. Sketch out your characters, yea, but start with the overall forms before adding details or textures. This is for your own benefit, as well as the benefit of the art.
I realize you're doing this for a game so you have a responsibility, but if not for that I would say take a break from pixels and study up on traditional art first. There a pretty good
resource thread here and an anatomy thread as well. Might not be what you want to hear but traditional skills are the foundation of all mediums, and everyone can stand to be better at them.
But you are working on a game so I would say instead, study up concurrently. Make some sketches of your characters on paper first, get them to look right.
Regular drawing practice is one of the best habits you can get into.
I also would recommend GraphicsGale free edition, it's much better suited to pixels and animation as well (animation in paid version, not very expensive).
Oh, also. This forum has a nifty zoom function, you can include your images in img tags like this:
And now you can click on them to zoom in, or ctrl+click to zoom out.