Translations:F.A.Q. - Frequently Asked Questions/30/en

First think about which service you want to use. Mastodon, Pixelfed, ...
Then think about the size of the server. Very large servers go against the whole idea of decentralization/federation and especially right now they might be overwhelmed from all the new users. Additionally, huge servers are much more attractive target for hackers.
Tiny instances might appear very sleepy and thus making harder for you to discover interesting people to follow, as you have to actively search to find them on other servers.
Then think you should ask yourself what is most relevant for you: sharing a server with people, who share the same special interest, or who are geographically located in the same area or do you want neither and prefer a general interest server.