Wellll... You should work on your everything... even at your point of view.
Do you have a drawing tablet? Cuz it seems you use a bunch of shape, line tool, pen tool, and the fill tool.
Start with paper. Get a quality paper meant for drawing, inking, and sketching to avoid those cheap notebook paper where it can wear down easily with loads of erasing.
And learn fundamentals of art. You don't know how to add shading because you didnt even bother learning the fundamentals of light and shading.
You actually should work on your people drawing before focusing on color and such.
I suggest what you do now and search the basic fundamental's of art, watch some tutorial videos on youtube (I suggest Jazza, Proko, and Sycra), and go back to your art thread and post help there.
And like what one of the poster in your art thread said, "Sucking at something is the first step towards being sorta good at something."
