Nice hands, keep it up. You don't have to add a second color, but with your eye it would take it to the next level!
Let it flow, don't try too hard to put it in a category, except that it's YOURS. Very few appreciate true, original art.
Not my style, however,I like it a lot for what it is,an original piece of art work.If this is you just starting,I'd be very interested to see what you come up with in the future. You should be proud of what you've accomplished! Good on ya!
Needs some flying saucers, and naked amazon warrior... wait ... that's someone else's fantasy... Looks like fun! Don't stop now... Keep going!