[Sombre]

These suffer from some common problems. You need to be less subtle with shading, you need more shading and highlighting to add definition and detail and you need to thin a lot of the limbs to make them less cartoony. I would also strongly suggest less bright base colours.

As for exactly how to improve these sprites, you just have to practice and get a feel for that yourself. Look at some of the more recent (and best) KO sprites and see how he shades and adds detail.

You're on the right track but these definitely need more work. Personally I find basic graphics a huge turnoff in a mod. I think the current warhammer chaos mod could use (along with some other things) more graphical work for example, before I'd play with it.