Not bad for beginner stuff, I should know, I'm a beginner myself. At least you're working small.
It's not readable enough; detail gets lost. I see half of an insect sitting on some odd blue orb thing. I see no indication of a robot.
Very shallow depth due to your shading and boring-directly-overhead-lightsource, which I doubt you even thought about. Think about light, it controls EVERYTHING we see. Use light. Use shadow.
Your palette swatches are wrong, where are the greens?
But, your biggest crime here is the incredibly cheap use of mirroring, that's one-year mandatory, pal.