There seemed to be confusion in the last workshop of how to do a ¾” Double Fold Hem. There are two schools of thought on the best way to mark and fold a hem and both will be shown here.
On the left, on the yellow fabric, is what I do most of the time. Mark on the Good Side, and fold on the mark. Some people have difficulty seeing the mark to fold it. Some people do not like the idea of making a mark and leaving it.

Plan B: On the right above, the white fabric, on the Bad Side, the side away from the flyer, the side where the hems are, mark a line twice as far in. This line will eventually be replaced.

Plan A: As above, fold on the line. Plan B, the white above, fold TO the line.

Left above, fold on the line. Right above, fold to the line.

At this point, using either method, open the hem and fold to the fold.

A magnet on the throat plate of the sewing machine really helps to sew a straight and uniform stitch for the hem. This is a Pfaff 2040 with a standard Presser Foot and the needle is offset 2 to the left. The magnet is right against the edge of the Presser Foot. The magnet could be spaced slightly to the right and the needle could be left in the center.

Above shows that the results are the same. Both pieces of fabric have a double folded hem that consumes 3/4" of fabric. The white, Plan B, fabric has the added step of erasing the line that was drawn to fold the hem.