Facebook, Twitter, and Instagram are the most accessible way to interact with people.
If you haven't done so already, create a professional Facebook page for your brand. Make your Instagram and Twitter follow the same professional outline. Post about projects you are in, tag yourself in photos, and hashtag your pictures with actor- related tags.
Make sure all the photos, posts, and statuses you are tagged in do not show you in a bad light. There should not be photos of you drinking, smoking, or doing anything illegal. Try to untag yourself from all of those photos or ask for them to be removed.
Any statuses where someone is talking about a strong political view, or is bullying, or is being prejudice in any way should have your name removed from it.
Casting directors, producers, and other hiring associates all have social media and they will look you up before hiring you.
You can follow casting directors, directors, and producers on Instagram and Twitter. Feel free to retweet some of their cool or funny tweets. Try not to go overboard and retweet everything or retweet it 3 seconds after they post. You can build a great relationship with people in the industry through social media.
Make friends and build up a following.