Piece of advice from someone experienced with federated social networks:
*Every instance will have it's own rules and communities. Check that first to see if it's for you and respect those rules.
*Not every instance connects with all of them. Check that too.
*Some instances will have technical limits, mostly because they're run voluntarily or made for small groups. If you can, support the admins.
*You can find information about the above on home/sign up/faq pages. Read first.
*Be kind and enjoy!