Very first project, need criticism/help

I just recently got into modeling and decided I was going to make a 1911 based off of this picture - http://www.resistthetyranny.com/wp-content/uploads/1911_l.jpg.

Here’s my progress so far. For some reason the render made the model shorter, so the trigger
guard looks smaller than it is.



I’m just wondering what I can improve on and fix.
Here’s my project file - http://www.mediafire.com/download/v31ku84ib4sv7bs/1911.blend.