I found this tutorial that I created in 2010 and never posted. I cut my strips 2 1/2" wide, folded them in half lengthwise and pressed them.
Starting the longer side piece
Trimming the binding length short enough so that it does not go to the corner, but long enough that the cut end will be under the end binding once the binding is turned to the backside of the piece.
So now the binding is sewn on each side and it is ready for trimming.
Trimming the edges. I trimmed my batting and backing about 1/2" from the stitching line.
Piece is trimmed the same all around, but now I trim the corners to get rid of the excess batting and fabric.
Trimming the corner
Corner trimming finished.
Pressing the binding
Long sides pressed and ready to turn corner
My turning tool. I must have dropped it at one time and broke the point off, but this is a good thing. Now I don't have such a sharp tip and there is less of a chance of poking a hole in the binding. The key is to gentlely push the corner out and not going too far. You have gone too far if you get a kind of bubble at the corner and it sticks out from the outside edges of your piece rather than being a smooth line to the corner.
Corner after turning.
Pressing the binding to the back side.
Ready for hand stitching