Amy and Zapp

I really like the idea and your general style but you should try to slowly expand your skills a bit. Especially in the face area.
Just as a suggestion: maybe you should consider upgrading your software. I don't know what you use but a lot of artist show of their software in tutorials on youtube. Might be worth a look.
Alternatively try to practice by drawing various sketch's without coloring them. Could safe time, which could be spend on the drawings.