and get out of your comfort zone ; - ; this is really important xD if something feels difficult or uncomfortable to do, the best way to deal with that is to practice until you're good. you'll be happy you spent so much effort when you've finally mastered it (or at least gotten pretty good at it)
i'm going through this right now with alot of stuff, including feet and hands, which i used to avoid mostly ; v ; theyre so hard
and lastly, I can't ive you any direct tips on here about your art work because i dont think id be much help, but practice coloring and shading as much as you can, because it is an extremely important part of drawing. The pencil work itself can really only go so far after all. Look up coloring tutorials and speedpaints on youtube and pay attention to the techniques they use,so that you can develop your own :B hope i helped a bit