hi kemal. i have illustrated a few bags for my company. There's a few things which I would try to improve. First is the bump on the leather. On your image, it looks less like leather, and more like a moulded plastic with leather texturing (i mean the literal definition of texture - having a rough surface). This is something i am trying to improve in my own technique as well
. Another thing is the leather looks incredibly stiff. Usually there would be some wrinkling or sagging somewhere (even on a very stiff bag). Maybe also you would see areas around the corners which are "nipped and tucked". Also i don't see any edges of the leather panels. Most panels are sewn on top of each other, so you see an edge. Or they might be sewn up within a round piping. Also i don't see any stitches... And here are some things which i think you nailed perfectly - the "inked" leather edge which is visible around the zipper, the pewtery finish on the hardware, the injection acrylic "tortoise" material of the handle. Those are damn near perfect!
shorty