Welcome
Nice start. For starters I'd recommend you don't scale it and post it at it's original resolution. (You can zoom by just left clicking a picture on the forums!)
A few thoughts:
There are a few stray blue pixels near his face.
The contrast is too strong between the colors, try to reduce saturation on some!
There are some anatomy issues which can be fixed. (Unless you want it stylized)
The hair looks wonky!
Establish a light source. It'll really pull together your sprites.
Also I'd recommend not using a pure white background, but that's just me.
Can you post your reference sprite? (if any)