Hang out! Networking neednít be stiff and formal, neither should friendships. Drop by their streams, hang in their Discords, interact via Twitter, show your support! It shouldnít be any more difficult than making friends with anyone else online, just with a slightly different dynamic as they may not be able to pay attention during casts.
Itís worth noting that it can be harder to befriend larger casters, solely because your voice can get a little lost in the flow of chats and feeds. However donít let this discourage you! If you want to be an integral part of a community, make yourself so. Be friendly, be a recognisable name that appears in as many streams as you can.