Most Helpful Guy
Looks good so far, you should add some shading to it and it should be good to go. But don't put too many hopes into selling your work without a "Name"! There are many people offering sketch art. You should consider publishing your first few works for free on sites like "pexels. com" to gather some attention. If people find your work interesting they will contact you on their own!
Most Helpful Girl
Yes I think these would sell, you could also do commissions! An easy way to sell them would be getting a tumblr account and sell then on there. You can message me and I could help you out because I'm an artist too and I'm trying to sell my art soon. Dont be afraid to message me, I would love to help you out. ☄