Howdy.
Welcome to the community 
First off you got some cool sketches in there. I particularly like the pencil sketches you've done.
I've also been there where you feel stuck, and I feel like I'm still there heh, so you're not alone. In the later pieces you've posted it definitely shows a better understanding of anatomy, namely facial anatomy.
If i were to offer any criticism it would mainly be on the picture of the archer chick, and the piece with the flowers. With the archer gal, I feel like she could use a bit more colours in the shadows and highlights. In life objects, people, environments change depending on the colour of the light source, it gives more life and believability to the painting when the shadows and lights aren't just higher or lower values of the base colour, try playing around with different coloured light sources. A good place to start would be perhaps checking out some videos on colour theory, colour harmonies, complimentary colours, what colours go well together, which ones don't.
A general guideline I use when painting light and shadow is to have a warm light source, and a cool shadow, e.g. yellow/orange light, blue shadows, or vice versa. Of course you don't have to apply this method to every painting but it might help as an exercise.
Having a focal point helps as well, to not have everything on the same level of detail, value, or saturation.
With the flower lady I think on some level the colours are all competing for my attention, and that my eye kind of gets stuck on her eye. Try to think about the composition of your pieces, where do you want the viewer's eye to travel, think about shapes, leading lines, things like that.
I suppose that critique is mainly addressing the pictures you've posted so far, and not so much the animation side of things. I haven't done much animation, but I would definitely think anatomy to be incredibly important in that regard, and studying how people, or whatever you're animating is meant to move.
To summarise this wall of text haha , do some daily sketching perhaps, an hour or two a day, or every two days, or a few times a week, just sketching people in various poses, or hands, or feet, or faces, wherever you feel you're lacking. I usually hit up Pinterest and just search "action pose" "running" "anatomy" "jumping", any combination you can think of, and try to fill up a page of studies/sketches.
Hope this helps!
Looking forward to seeing more!
