Some of the colors you used to shade is a little too close to the original color. Plus you changed the light source on both of your characters. (to the right on the first one and to the top eft on the second one.)
My suggestion is to refer you to another message else where.http://pixelation.org/index.php?topic=20962.msg177962#msg177962Character size is about the same, of course gender is different but the overall proportions are similar, what differs is shape. So keep that in mind.