Coin Quilt Question

Hello~
I am a new quilter and am making my first "coin" quilt.  Does anyone have suggestions on how to keep my long coin strips from getting a little warped?  Do you just square and trim when done?  My coin stacks are 22 coins each.  I am using a layer cake, so I am dealing with pinked and cut edges.  Thank you.

I don't know why, but I read that if you sew a seam in one direction, sew the next one in the opposite direction and this will cut down on warning.  I have tried it and it does work. 

Yep- I totally agree! Sewing in opposite directions with each new rectangle is crucial. As you sew, you will stretch out the fibers and if you do not go in the opposite direction, the stretch will become more and more exaggerated. The worst part is that you don't notice it until you have a sewn a few together. (I did this on a strip quilt recently and didn't notice until I had sewn about half of the quilt together!) 
If your stack is really warped, you might want to consider ripping out a few seams and re-attaching in the opposite direction.