|This tip just appeared in Threads, but I've been using it for quite a while. I don't know why it never occurred to me to add it here!
I've never gotten the hang of using tagboard templates for marking and pressing up hems. Instead, what I do is mark twice the hem depth on the wrong side of the garment with chalk, then fold up to the mark and press. The Threads tip suggests that you first fold over and press the raw edge, then mark twice the hem depth, fold up the hem, and press. I press the hem up first, then fold over the raw edge.
I also don't use a seam gauge. What I've found works best is a square 6-inch ruler (mine is made by Omnigrid, primarily, i think, for quilting). I place the ruler over the fabric, matching the raw edge with the grid line for twice the hem depth, then use chalk to make a continuous mark. As I move the chalk along, I pivot the ruler so that it follows the curve of the raw edge. It takes a little practice, but results in a smooth curve, and is very quick to do.
Once I've turned up the hem, I use the ruler and chalk to mark the line for turning the raw edge under. Because you can see all the marks (you aren't turning the fabric over them), I find this technique easier to do than to mark inside the hem line. And none of the marks will show on the right side of the garment.