There are so many things you can do it would be difficult to know where to start. I would suggest running down to Barnes and Noble and buying Robert Harleys "Complete guide to high-end Audio." He has a least one chapter on your listening room with lots of helpful hints. If they have the book in stock look through it for a while and see if you would find it helpful. I thought it was worth the price of the hardcover but for a little less money you can get a softcover version. There are system set-up tips and vibration dampening advice. I would think his tips will be more helpful than most of what you get here simply because you can use his guides and fit them to your situation.
Best of LUCK!
Best of LUCK!