What is a one-sentence summary of the following article?
Have the tutu-wearer-to-be stand still, with their back straight.  With a measuring tape, measure from their waist to the part of their leg where the tutu skirt should end. Most tutus fall between 11 in. (28 cm) and 23 in. (58 cm) from the waist. This will ensure it is tight enough around the waist. Adjust it, if necessary.

Summary:
Take waist measurements. Have the person try on the elastic.