Hi there, welcome!
I really like your sketches. The digital art could use some work, but they're pretty solid already for you being so young
A few things I'd improve on:
- The highlights are very tiny and scribbly, I'd make them a bit larger/blurred out and less white.
- Try to sketch the anatomy and proportions correct before going into any detail or colour. I can't say this enough to aspiring artist: first get you sketch working. Because no matter how much you render and polish, the drawing isn't good when things are off.
You rendering looks nice, especially the hair. Good luck