Hi new people! Enjoy your stay! Be friendly, use #introductions, find cool people to follow on the federated and local timelines
For some mastodon.social might be the gateway into Mastodon, but Mastodon is bigger than mastodon.social - don't be afraid to branch out to other instances (using https://instances.mastodon.xyz/ for example) - you get access to all the same people but from a slightly different starting point, like choosing a neighbourhood in a new city