I am not a dancer, nor do I play one on TV, however, I highly recommended these FootUndeez.  They are spelled differently elsewhere, but the "undies" comes from their design, as you can see from the photo.  They have suede patches to protect the ball of your feet and if you are a dedicated sandal-wearer, as we are in Florida, they also keep the thongs from rubbing if you have some serious walking to do.  You can rinse 'em out in the sink and they dry quickly. They have different styles, which are made out of slightly different stretchy material, so check the reviews for sizing on different fabrics.  The solid colors (some with tiny rhinestones) are a little thicker and have less "give" to them, so can be a little tight at first.  Great for vacationers; they are small enough to stick in your pocket to carry in case your feet get sore from walking in flip-flops or sandals.  Oh, I'm sure dancers will love them too!