Covered my TV...What next?

I am a newbie to higher end audio and recently acquired some Magnepan 1.6 speakers that I am enjoying very much. My speakers are about 5 feet from the back wall of my room which is 25 by 23. I have a 50 inch plasma tv between the speakers that is not far from the back wall. I have hardwood floor with no rug, but the windows have fairly thick drapes. Walls and ceiling are drywall.

This evening I decided to experiment and put a blanket over the tv, which I had seen suggested. I was suprised that it made a noticeable difference. Certain instruments seemed much more distinct and almost seemed louder than with the blanket off the tv. I assume this what people mean when they say the glass on the tv "smears" the image or sound.

This bit of "success" has me interested in trying to improve my room. Any suggestions for other things that might make the biggest difference -- that is, biggest bang for buck and reasonably practical? I do have the WAF to contend with, but the blanket is something that I think can be pulled out of the closet when needed.

I have also read a little bit about dealing with first reflections. Is there a particular area (e.g., back wall? floor? side wall? ceiling?) that would best respond to some type of treatment (I assume absorption) with the Magnepans?

Thanks!