Thought I'd talk a bit more about preventing flares and such instead of just the measuring part.
I'm a pinner because I believe in it. I didn't want to be a pinner, I have friends who can do all sorts of things with hardly a pin at all, but for me, pins every couple of inches every seam are the answer. Add to that, that I also press open and so every leading seam has a pin, sometimes there can be a lot of pins on a seam! If it is needed, I will mark center or other points with pins on the right side of the fabric, or pencil marks on the back. Center is easy,just fold in half to find.
Along with that, I am a prewasher and presser. I don't like ironing either, but I believe it is key to my success. If your fabric isn't ready/right and floppy and wrinkled or other issues, it isn't going to get better. When putting on borders, I'm often working at my ironing board as it is one of my larger work surfaces. Typically, if the border fabric is solid that will be pressed on to the board (right side up) and then the top placed, centers matched, and the top lightly pressed into place and then the leading edges of the seams pinned down.