Hi Debbie,
1] I don't fold my material
2] I use Best Press first on all the material before cutting.
3] I mark one diagonal on each of the squares ... making sure the fabric directionality isn't compromised, just in case.
4] I put one of the squares at one of the ends of the rectangle and then sew just to the outside of that diagonal line, by maybe 1 or 2 threads, of that diagonal.
5] I then fold back the square to make one side of the FG to check for fit. If it fits, I iron it in place then I trim the bottom 2 layers, though many don't do this trim step.
6] Then I put the other square at the other end, in a mirror image of the first square. The first few times you do this you might prefer to pin it on what will be the sew line, then crease the material back to make sure you have the diagonal line going the correct way.
If all is well, sew like the other square, just inside the diagonal line, fold it back to check for fit, checking that where the V is is 1/4" from the edge. Then iron, and trim, if you want it trimmed.
Unfortunately my camera is packed to go so no pictures at this time.
Maybe someone else can post the pictures or PM me and I'll do it as soon as I can.
ali