How to get in touch with the prospective clients

I've decided to develop a tool which could be useful for the marketers and affiliation (according to my view).
Do you know how I could get in touch with them in order to understand how they work and ask some questions ?
Is there any forum or platform to discuss about it ?
It's very important for me because I need to have all the required informations before beginning the development.

By the way, if you have some tips or articles about this way of work (ask before coding), do no hesitate to share it :)