Shannon,
I measure through the center then cut that measurement, but I use the length of the fabric then tear the fabric for the width of my border. I also take and divide the border into 1/4's and my quilt then pin at those marks and distribute evenly. Once the sides are on I then measure for the top and bottom the same way. By tearing the fabric it is on the straight of grain. I also have started straightening my fabric before ever cutting tear across each end then match the sides if they aren't even stretch on the bias till they are works best with 2 people to do.
Elayne