First, let's draw the top half of the skirt. Ballet skirts usually look like suspenders. I can imagine it at once. Just draw the part that covers the upper body and add two shoulder straps to hang on your shoulders. If you want to make them more elegant, longer or add bows, you can draw shoulder straps at will.
Then we draw the lower part of the skirt. Ballet skirts are generally fluffy, and the skirt is not high. Finally, we make up the lace and pleated lines of the skirt and then color it.