I have just starting dating someone recently and like you was wondering how to subtly bring my sexual preferences to his attention as I didn't fancy getting into another relationship that wouldn't totally fulfill me. He is very dominate and in control in his life and I was hoping he would be so in private too.
So, on our first dinner at pudding time I asked if he preferred vanilla ice cream or something a little more interesting (a line I had in my head all night to get in!) I don't think he quite got my meaning but said definitely something more interesting which at least gave me hope!
After spending a little more time together we got into some naughty texting so I took the bull by the horns and asked him to tell me one of his fantasies, he replied with this... "I want you to totally dominate me sometimes. I'll do anything you tell me, you can do anything you like with me, I will be your sex slave. But sometimes I want you to be mine."
I am jumping back flips!! (Just as well I am switch!!) I never imagined that I would meet someone kinky through a friend of a friend.
So, my advice would be to find a way you are comfortable with to tell him what you want, you could spend weeks dropping the hints or just go all out and ask the hard questions!! Just think, if he says yes and he is a kinkster, you might kick yourself at how long you wasted hinting when you could have been playing!!