I have discovered a relatively easy way to decide where to put my furniture - to experiment with different arrangements, to see how a particular arrangement will flow, work, and look - without having to call up a bunch of friends to help me (or drag the sofa back and forth by myself)!
Creating a scale drawing of the room you plan to rearrange (as well as scale cutouts of the furniture you will be arranging) takes a little time up front, but is worth it in the long run.
I have also used this technique upon first moving into an apartment, to decide where the furniture goes in the first place. It is easier to measure the rooms before I have all my crap in them, in any case. :-)
Okay - are you totally pumped for this? Let's begin with Step 1 - Gathering Necessary Tools And Materials. All right, let's move!