First off, welcome to 'osity. :) There are a lot of talented people lurking behind the curtains here. ;) Now, to the image. Only one word really: Scale. The ashtray is huge compared to the depth of the desk. The open window, judging by the open area, extends into the wall beyond the frame. The water cooler, based on the size of the chair behind the desk, would require the person using it to kneel on the ground. BUT, this only applies if youre going for realism. Some of the greatest works in history are nowhere near scale. :) Overall though, its a great start! Far better then I did at first. ;)

The doctor says I have way too much blood in my caffeine system.