Keeping My Letters Neat

To keep my margins straight as I hand write a letter, I use an under-sheet that I created on my computer with a bold-lined frame. To help me find my centerline, I use a folded sheet of stationary overlapping from the right-hand side. These two simple tricks keep my letters neat.

My folded sheet, under sheet, and letter-in-progress spread apart.
My left hand firmly holds the stationary overtop the under sheet while I write.