Start with a bra that must fit perfectly so that your breasts do not accidentally fall out while dancing. It must also have a metal underwire.
Cut the straps off the bra.
Buy fabric that roughly matches your skirt and hip belt and cut out pieces that are just slightly larger than the bra's cups. Sew those pieces of fabric onto the outside of each cup.
Sew the strap material onto the top of each cup where you cut off the original bra's straps. Sew two more pieces of this material to either side of the cups so that you can tie the straps behind your back.
Attach adornments to your halter, such as coins or beads.
Use the holes in the coins to sew them onto the edges of your bra, or thread the coins and sew the loops onto the bra. You can do the same with beads. Make sure to sew something over the piece that connects the two cups of your bra.