If you're unsure of how to wear a strapless bra they fit in the same way as a regular bra, so a good place to start is your normal bra size. A good fitting strapless bra should fit firmly around the back, so it can give the support you need but it should be comfortable. If you usually wear your bra a little looser around the back, you might need to go down a back size in a strapless bra (remember to go up a cup letter to keep the volume the same!), or if you find a strapless bra too tight in...