Try your garment on and pin the hem to the desired length. Ask a friend to help if you find it difficult to do this on your own.
Take your garment off and carefully turn it inside out. If you are working on material such as a curtain, turn it over and lay it on a flat surface.
Adjust the pins for a more precise measurement. Check that your hem is turned up an equal amount all the way around, using a ruler or tape measure. If you are hemming sleeves or pant legs, measure them both to check they are equal in length.
Cut surplus material off, if necessary, with dressmaking scissors. Your hem should only be 1/4 inch to 1/2 inch.
Preheat your iron to a silk or wool heat setting. Read the directions on your hem tape package; some brands recommend using your iron with steam, while others do not.
Iron your hem to form a sharp crease. Remove the pins.
Place your iron-on hem tape, with the adhesive side down, inside the hem and sandwich it between the fold. Press your iron on one section of the tape and hold it lightly. Follow the manufacturer's directions regarding how long you should press your iron down. Continue around the entire hem until all tape is attached.
Turn your material right side out and iron the entire hem in a sliding motion. Leave it to cool completely before wearing or handling your material.