I like your Evily, Skeleton, Witch theme!
It's a clever design
I like the main colours you used "Black, Brown, Green, Dark blue for skull and hands" these colours used really pops out, plus the simple shapes, and colours used fits nicely!
Something cool and unique about your design, is the hair and the cauldron. Furthermore the boots and gloves are done very good, with holes and the rough sharp edges, making it look old.
There is one thing that I would change, and that is making the potion by her waist become bigger. Because it's hard to see the potion that small.
I hope my advice has been helpful to you, and keep up the GREAT work! :D