Good effort buddy. I'm sorry but anatomy and geometry are the main issues though, fat legs, skinny arms, skinny mouth, I'm sure with the current polygons it would only take some scaling and adjusting to actually fix the anatomy, the polies around the torso, sorry, but ouch, to put it extremely bluntly, looks like you've done what I did when starting and went ahead with yourself.
It's a start, you can look at general character modelling tutorials and general character model wireframes to see how you model should look, even if they aren't specifically for your program, they always help.
Also it looks to me, you've only used the subdivision and extrude tools, there are others tools you can use that will do a better job, it can be best to make use of different methods on one model, except subdivision in this case, there's more than one way to smooth a model. For that point I have a couple of tutorials there:
http://seppuku-arts.koetsuaboshi.net/?q=node/16
http://seppuku-arts.koetsuaboshi.net/?q=node/8
I hope they help. And good luck.
[edit]
Just noticed this is for a game, optimal use of keeping it low poly is essential, try to avoid useless polygons, because they actually decrease the performance in your game
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