Sophie's back with some fantastic fetish flogging bit of fancy!
Flogging is one of those not-really-a-fetish fetishes that's practised, in the majority of instances, as part of a different, broader fetish. In this case, that broader fetish would be anything that could feasibly include punishment as, in its traditional role,flogging was used as such, and people who willingly submit to it are often doing so in a sadomasochistic context.
In most instances, 'flogging' is restricted to certain fat, fleshy areas like the buttocks, and is done using a flat paddle or similar so the pressure is dispersed over a greater surface area, meaning there might be a little bruise but won't be any broken skin or mid-term damage. That's why only the hardcore use a cat-o'-nine-tails or any implement with blades on the tips.
However, even with normal flogging there are a few safety issues you should be aware of. Most people will tell you you can't flog the head, neck, face or toes and you have to be super careful when flogging body parts like the palms of the hands, any joints of the body, the kidneys or the lower ribs. "But at what kind of speed should I be beating my loved one?" is the logical next question, and I am sure where you just arrived.
According to Joblobbs.com, that's up to you, but their advice is: "Average one stroke every few seconds often proves best… this 'blow-rest-blow' allows processing time to feel each sensation, and this rhythm, once established, may easily be changed for effect."