Clean the surface of your glass ornament if necessary.
Begin by putting a small line of hot glue around the very top of the ornament and then immediately laying your twine flat on top of the glue.
Repeat this over and over again until the ornament is covered. (Line of glue, press the twine down on top of it, repeat).
Cover twine in Mod Podge using a foam paint brush. At this point you can let dry and leave as is, or you can add glitter.
If you are adding glitter, it is easier to work one half of the ornament at a time. Pour the glitter over the ornament until the desired coverage is reached.
Repeat on the other side. Hang to dry for a few hours.
Video
Notes
Be sure to pour the glitter over a bowl or something similar to catch all the excess so it can be reused.