Effective networking involves connecting with people, oftentimes through shared interests. Technological tools such as LinkedIn can inform you of upcoming events and allow you to connect with people all over the world. Use LinkedIn as a preliminary method of communication and ultimately transition to a phone/Skype call, and ideally an in-person meet-up.
While building and expanding your network is important, maintaining it is equally if not more important. Stay in touch with people you meet and check in with them regularly. This tactic will pay dividends when it comes time to look for a job or reference because the people you will reach out to are already established connections. Therefore, these people won't feel that you are only getting in touch because you need something, and will likely be more receptive to the idea of helping you.
While building and expanding your network is important, maintaining it is equally if not more important. Stay in touch with people you meet and check in with them regularly. This tactic will pay dividends when it comes time to look for a job or reference because the people you will reach out to are already established connections. Therefore, these people won't feel that you are only getting in touch because you need something, and will likely be more receptive to the idea of helping you.