I think what turns me on most is the idea of handing over complete control to someone else. I am very independent and a bit of a control freak in everyday life, so handing over my body to someone to use like an object.. I get hard just thinking about it. Body worship really turns me on, and I'm getting more into kinks like piss and degradation. One of my biggest fantasies is to find a hot dom to force me to suck is cock until he comes in my mouth, and then I'm not allowed to remove my mouth from his cock until it goes soft and he empties his post-cum piss in my mouth.
The idea of being a dom turns me on too, but I feel like starting as a sub is a good way to go.