As much as I hate to say it, linkedin is extremely valuable for this. When we were getting our business off the ground I wrote connection request messages to t

As much as I hate to say it, linkedin is extremely valuable for this. When we were getting our business off the ground I wrote connection request messages to the C level guys in large companies we were hoping to work with. I was honest and said that id like to talk with them just to see if what we were thinking of doing was something they would be interested in. A lot of them responded (especially ones from start-up backgrounds) and the resulting discussions were extremely positive. Even where we didn't end up working with them we learned a lot. But most of them are our clients/partners now. Its amazing how many people are just happy to help. Im my experience the lowest & highest levels of the companies are the easiest to approach. If you would like to connect with people but they are not in your network a good idea is to connect to headhunters or people who post a lot in that industry. It shouldn't take many to build up a network of 2nd level contacts you can send a connection request message to directly.