Hokay, enough ten-word posts. (Oh, for the 100-char rule back...)
First off, I'd like to agree with Helm that uncropped canvases are annoying. If your sprite is 40x80, you don't need an 800x600 canvas. That's wasted white space. It takes ten seconds to get rid of, even in paint.
That said, on to the critique. This piece really doesn't have much to critique yet; it's barely started. The guy is still off-balance; he needs to lean more to the right if he doesn't want to fall over. This is true even if he is leaning around a corner. Leaning around a corner is still leaning, and you'll fall if you lean to far. This is only false if you are holding on to the corner, which he is not, considering he's holding a gun. The legs are too thin; they look like toothpicks. He appears to be a soldier. Soldiers are muscular and have meat on their bones. The arms are blobby and unproportional, and might be a bit too short.
To sum up, this is barely started. I critiqued some stuff, but all of it could be fixed in about 5 minutes and is mostly irrelevant because it could be summed up by a comment on the very preliminary stage this is in. Do some real work on this, show us clean forms, and we can provide more helpful critique. You've made progress in drawing legs, now show us clean legs. Good luck!