Hey! What's your art experience and human drawing experience? A character like this requires a bit of knowledge on human anatomy. It'll require some study and a lot of practice to get decent at anatomy. Anyway, your character reminds me a lot of this PC fighting game (lol) called One Must Fall 2097. I suggest you look at it. The robots are made out of simple angular geometric shapes.
In regards to how to make it better, I would say redraw the body giving specific masculine or feminine features. Broad shoulder, wide hips, big biceps, slender frame, etc. I think you've got the basic human proportions down. I think you need a more interesting robot shell or exoskeleton too. I'm not saying you need to go realistic but your art isn't working right now. Take a look at Star War: The Clone Wars cartoon for a stylized, simplified style.
Again, check out One Must Fall 2097. Not that it's the best game but some robots are pretty interesting looking. It's worth a look and it could inspire you! Good luck!
http://gallery.dpcdn.pl/imgc/Tools/68393/g_-_-x-_-_s_68393x20151124100305_0.jpg
