The whole white BG thing.
A number of big rules.
Light spill is the enemy. It will cause edge destruction (the last image).
Too much light on the BG will cause all lenses to struggle to preserve detail and contrast.
My setup guide would be:
1) Get the BG light sorted. I would suggest that the BG is *just* clipping. Set the camera to show the image with 'blinkies turned on' flashes the image where the exposure is clipped.
Set the camera to manual at the aperture you want for the subject - say - 1/100th, F8. Then slowly increase the BG light until it starts to clip. You will need to get the light as even as possible over the BG. You should be aiming to over expose the BG by as little as possible.
2) Get the subject into shot as far from the BG as possible to limit spill. You can even flag the BG so that only the smallest margin around the subject is lit.
3) Set the subject lighting.
In an ideal world with only the subject lights on the subject would be nicely lit against a BLACK BG. With only the BG lights on, the subject should be a perfect silhouette.
This is almost impossible to achieve.
Both shots below are not too far off straight out of the camera. Minimal alterations. Although lightroom is very good at overexposing any of the floor that needs to be "whitened".
This is with the BG set to F11 and the subject shot at f8, subject is about 7 feet from the BG:
The last thing to consider is the floor. I use a shiny white floor made from panels intended for industrial shower/bathrooms. I reckon this looks LOADS better than the white vinyl that a lot of people use.