Choose a plain leotard in the color you like. Wash and air dry it.
Add embellishments to the leotard to customize it. Sparkly fringe looks great across the entire leotard, or glue lace around the sleeves. Cover the whole thing with rhinestones for an ultra sparkly look. Use your imagination and get creative. These items can be hot-glued on, or you can sew them on with a sewing machine.
Make a tulle skirt to go around the waist of the leotard. A simple way to make a tulle tutu skirt is to measure your child's waist and cut a piece of elastic to fit her. Sew the elastic together to make a circle. Cut long strips of tulle. Four yards of tulle generally makes a nice-sized skirt, though you can use more. How long the strips are depends on how tall your child is and how long the tutu will be. Tie the tulle strips on to the elastic using a regular knot. Use as many strips as you want, and vary the length and width of the strips to make the tutu more puffy. Make sure the knots are aligned. Tie ribbons in between the tulle strips to jazz it up a little bit.
Add a feather boa around the waist or sewn on to the leotard for a fancy finishing touch.
Dress up your outfit even more by adding sparkly tights, a tiara, or funky gloves.