Looks good so far. But yeah, I agree with what the others said. If you're using a mouse I'd put some money into a drawing tablet. Especially for vector art. Here are some links that could help:
I personally use a Huion Tablet. It's a few years outdated, but it still serves it's purpose:
I've heard good things about Wacom Tablets. Don't use one myself, although I know many people who could swear by them:
And last but not least, since everyone has a different preferred Art Software, here are a few links to help you decide:
12 Free Design Programs
A Programmer's Guide to Creating Art for Your Game (Vector Art is the third section down)
5 Best Free Vector Graphics Editors
Hope this helps!