In my experience of dating sites (I had lots* in the dim and distant past), the things that would provoke a response were those who had read my profile and thought about their approach. Trouble is I don't know how men think (you'd think after all these years, I'd have half a clue).
Thus say a profile says "I enjoy dining out". Your opening gambit could be "Hi, Your profile reads very well. I love dining out too. I am very lucky there are some lovely places near here to eat. What is your favourite type of restaurant?"
That breaks the ice slightly better than "hi". Which will probably get the response of "hi", then you have to go back with "how are you?", and he'll come back with "fine, how are you". That's like pulling teeth.
*experience that is, not men