From the photography side these look 3d because they are. One of the comments has already mentioned the ghost manikin effect where they are placed on a body but the body has been edited out.
The other most important thing is light. In order to get the look you're after you need at least one larger light source that is going to provide the subtle shadows that will give it dimensions.
Light source i.e. off camera flash
Diffuser (Preferably with a grid)
Transmitters/cable to connect to camera (you can skip this if you've rigged it up with a permanant light source)
Camera - nothing special, just needs to be able to work with the off camera light probably a second hand DSLR if you don't already have one.
Tripod would be handy if you see yourself doing lots of these