At conferences, don't seek only those whom you think will help. Much of building my platform has come from other people who—unasked—opened doors for me.
If you can, join professional groups. In which online groups do you participate? Publishing (like many businesses) is built on relationships. The more visible you make yourself, the more you grow and the greater your exposure and influence. That helps build your platform.
1. What professional groups have I joined and remained active in?
2. Which online groups or conferences have benefited me?