Place the cardstock on the table and measure the desired hem on both ends of the cardboard, lengthwise.
Place the ruler between these marks and trace a deep strong line between the marks.
Using this method trace various size hem guides on the cardboard so you'll be able to use the same hem gauge on more occasions, for different hems. I traced 1", 1/2", 1/4" hem guides as seen in the photo above.
Place the fabric with the wrong side up and align the hem gauge with the edge of the fabric.
Fold the fabric over the hem gauge until it reaches the desired mark line on the gauge.
With the pressing iron on steam press the hem down.
When the hem is folded all around the clothing item repeat the process.
Sew the hem down as close as possible to the inner fold (I normally sew about 1/8" away from that fold).