I use LinkedIn by simply adding whoever seems interesting, without adding an intro or note to the request. I reach out only when it seems I need their services,

I use LinkedIn by simply adding whoever seems interesting, without adding an intro or note to the request. I reach out only when it seems I need their services, for example if I want to work at the company they work for. LinkedIn also has the advantage of being exponential in the connections you can have due to second and third order connections; when I add one person I also add their entire network.