Originally Posted by MamaHen
Hold your fabric up-salvage to salvage, now move the front salvage piece left to right- right to left, until the fabric looks straight from side to side. If you see little waves in it, it is not straight. It takes a little practice, but it helps. I find that more than a yard or so is a bit much to hold. I also found that if I press out the middle fold, the fabric will fall straighter. Good luck.
I do this after my fabric is washed and dried. Smoothing from the middle to the edges is a definite! I have done this with as much as 4 yards of fabric, all spead out on the (vacuumed) carpet. It IS easier when you have someone else on the other end!