It's hard to tell if you're improving since you've only got like 9 things in your gallery, but I will say that your character ideas are pretty cool. The actual craftsmanship of art, like rendering, perspective and such are just something you learn through a lot of study and practice. That sort of skill just comes naturally by drawing from life and studying for the purpose of learning. The design and stuff are your strong suit, so now all you need to do is draw an outrageous amount. Good luck man.