Melissa, I think saying there's rules is sort of over the edge. I don't think that there's rules but there's certain feelings or emotions that you most certainly are aiming for. I have never done one of these shoots, but if I were going to I immediately do my homework to find out how the guys that are the best, do what they do.
I would look at
Tony Yang His lighting and angles are fantastic. There's also something that you need to work with the models on. They need to feel hot to convey hot. That sounded really stupid. But I'd make a CD of the sexiest music I could find and just have that rolling in the background.
Also study the lighting, exposure and posing of
Onyx This is way beyond what many of us could pull off, but it's your inspiration to push yourself.
Again I don't do this stuff, but I've always wondered what these guys' settings are, what lights do they use. All that goes into these shoots is crazy and you really have to be creative and ask yourself, your clients, friends, husband, What is sexy like? What does it look like? Feel like etc. Just my initial input.