Making your environment less hectic will make your mind less hectic. Try to keep only the project you are working on in front of you. Things like desk clutter, dozens desktop icons, a crowded workspace, too many people, or anything else that catches your attention will invariably hurt your performance.
Every single item you see or sound you hear will trigger some new thought. They stimulate your brain, diverting its attention. Steve Jobs insisted on complete bareness and simplicity in his spaces—he was a minimalist to the extreme, and he was a pretty productive guy!