Bluetooth Tag

I am trying to build a wearable Bluetooth tag as part of a project,
I have the software that I can use but the tag must be built from scratch, so I can start with an Arduino board but from there need to select all the components needed and design my own PCB and populate.
any help would be greatly received, need to know what parts, schematics, code whatever really, I have no idea where to start.
:smiley: