You want to get better and you want to enter the world of digital arts. How much better? What is your ultimate goal? What do you consider good? Will you be going to school for digital art, or are you trying to go to school for digital art? Is this just a hobby?
These are important questions to ask yourself before seeking critique. Just saying "I want to get better give me advice" isnt very useful, even if a pic is posted, because people dont know what direction you want to go in. We need a basis to compare you with "I want to be good enough to make my own comic/game/movie/brand/sale and commission work" "I want to be as good as *insert artist here*" "currently my work looks like _____. Im hoping to be able to get it similar to _____."
Its hard to give someone direction when we dont know the goals. If I were to critique your current stuff based soley on what information your provided I would be using too much of my own personal preferences towards art and the critique, while being possibly helpful, could ultimately be misleading. Personally I hate antro art so I would say right off the bat drop that stuff, especially if you are thinking of going into digital art expecting to make a living. And I would also go against the previous commenters and say the only good part of the piece is the cross hatching, heavy uniform line work like you have is a sign of inexperience and is just all around ugly. Your color scheme and usage also screams beginner to me.
See what I mean? Those could all be relative points, but if your objective is to make say, a webcomic with a certain style similar to what you have, then the critique would differ greatly and the one I gave wouldnt really apply any more.
Plus if you are planning on going to school for digital stuff an entirely different critique would be needed. That one would revolve more around getting a cohesive portfolio together, rather than general "improvements". Most of the improvements you would pick up in school.
With pictures that plain and generic its important to provide a bit more information than just "tell me how to get better." Its about as useful and vague as grabbing a bag of flour and saying "i have this, now tell me how to bake something, but it has to be the right something"