Hi Cosmic,
Okay so I'm not a bit of a novice so I cant give you loads of advice on colours, style, skills etc..
What I
can do though is point out that the way you've drawn this is a bit strange :p you've used actual pixels to try an "build" bigger pixels? As in, some of your "pixel blocks" are 3x3 pixels, others are 4x3, its all a bit confusing. Did you draw this and then scale it up in another program? Even your background isn't transparent, it literally grey and white blocks put together :p
You should create your pixel art at a fixed resolution and make the best of each pixel. For this case, try drawing your character again on a blank canvas of 20 pixels wide and 30 pixels high for starters.
Another tip: you dont have to scale your art. Just upload it at its original resolution and we can just click on it to zoom in ourselves