Beep,
as you've already devine, the 1st thing to do is get the speakers in the optimum position. Raise them up so your nearfields have unimpeded access to your ears. A world of difference. Books, stands, bricks, whatever. The heavier the better.
+1 on Bit's suggestion.
But the second cheap thing to do is dampen the area behind you, to attenuate those reflections coming from behind you. The standard SOS suggesion for singing is to hang a duvet (quilt) behind your position.
Another cheap thing to do is make some bass traps. If you are like me, putting together frames is another skill you might not want or have time to learn. You should be able to find burlap bags for dirt cheap. At the farm store I picked up a couple of big burlap bag - the ones I got were stamped for coffee. They were 2-3 dollars each. Pick up some corning (pretty cheap too) and just lay it in the bag, fold the top and staple it closed (you don't want the itchy stuff floating around). You can put those up on the walls/ceiling etc.
Even a special built room and tuned is a compromise. Turning a spare apt. room into a recording space is even more of a compromise, but it doesn't (usually) mean having to put up w/ a bad room. You can get most room acceptable with a little aborption and reflection if you use nearfields.
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