I have a method for sewing ends together that I think is foolproof! Well, most of the time. I leave tails at both ends of the sewn on binding, but they don't have to be so long. They only have to overlap as much as the binding is wide. If your binding is 2 1/2 inches wide, that is how much they should overlap. If you start with a 10 inch tail, stop about 16 inches from that start when you come around at the end.
When your binding is sewn on with the two ends loose, pin these tails so that they are as snug as you want them. Lay both binding tails down, one on top of the other. Fold a triangle at the end of the beginning tail. Cut the longer binding tail at the base of the triangle pressed in at the beginning. Now the two pieces will overlap just as far as the binding strip is wide. Take out the pins holding the tails down, pick up both tails, open out the binding fabric and place right sides together. Twist them so that they make an ""L" shape (the 90 degree angle) and the pressed line is going side to side. The point of the "L" will not be sewn. Sew across on the line you pressed. Snap it straight and lay it down to be sure you sewed it correctly. You can still change it now. Then cut out the seam allowance, finger press the seams open and sew it down.
Make a practice piece on a potholder and I think you will be able to figure it out. Some tutorials come close to this method, but cutting the second tail at the base of the triangle pressed in ensures that it will fit when it is sewn.