This tank was probably one of my first embellishments. I started with strips of chiffon/organza. At first I started using fabric glue to attach it to the tank top but you can see it through the fabric. So I got out the sewing machine and just sewed down the middle of the ruffles.
Organza/Chiffon Fabric - cut in strips
Sewing Machine or needle & thread
Zero - it is no pattern or order and there are times that I even sewed off the organza.
The only thing to note is that if it is a really stretchy tank top, sewing this will make it not as stretchy so you may want to gather it to allow some give.