Join 500,000+ artists on ConceptArt.Org.
Its' free and it takes less than 10 seconds!
If you prick us, do we not bleed? If you tickle us, do we not laugh? If you poison us, do we not die? and if you wrong us, shall we not revenge?
seems like you have some idea of anatomy but it also seems like you're drawing from photographs for most if not all of these...nothing really wrong about photoref just make sure to get some lifedrawing in at some point. The thing that jumps out at me most is the lack of contrasts or inapropriate contrasts in your pics. What I mean by inapropriate is that the contrast distracts from the rest of the pic and brings focus to something which perhaps is not very important(like the black Bunny pic behind the girl in pic 3, the focus should be on the girl but the eye is drawn to the poster behind her). Also I'd recomment practicing your shading strokes, aim for more of a gratient and avoid texture unless the area you are shading has that particular texture or unless you're going for a certain effect. Right now the strokes like the ones in pics 3 and 4 are very distracting and take away from the overall image. Practice making shading gradients with the tools you normally use, avoid smudging with stuff like pencils or charcoal unless you're really confident in what you're doing. Also try to form longer, more continuous lines instead of making lots of short lines to describe your shapes/forms.
hope that helps