Position yourself as an SME! Being recognized as a Subject Matter Expert (SME) is a good way to attract people with similar interests who value similar expertise into your network. They will find you, so you will not have to work as hard at finding them. Of course, this assumes that you really have an expertise in some subject that is of interest/value to others. Think about what you are passionate about. Chances are that you are or can be good at something for which you have a passion. As long as that relates to a direction in which you want to grow your network, you have a good start.