The Fediverse may seem like a challenge to use for users coming in from Twitter, or else where. (Meta maybe?)
Here the some of the top challenges I had when using the Fediverse.
1) Picking a 'platform' to join.
Do we call Mastodon and Misskey platforms? I always looked at them as software interfaces for the overall Fediverse. Finding a 'platform' to join is simple. Or it could be the most complex decision in your life. Just pick an interface that suits you, you should be able to connect with the rest of the Fediverse. I did find that I would sometimes have to go to other servers ad copy and paste links from specific profiles to get them to show. (Not talking about banned profiles but profiles that aren't federated in the server yet) This is more likely to happened in the smallest of servers, and also when you look at federation from say Misskey to Mastodon.
Another quick detail is there are alternative web interfaces (Mastodon comes to mind) I don't know of any alternative web interfaces to Misskey.
2) Finding a right server to join. If you are coming into to the Fediverse it can become harder to fit in if your own chosen server doesn't a line with you and your hobbies/mindset. (rule and guidelines/inforcement) I would suggest you don't join the default server, as it won't be catered to you and you'l likely get lost there quick in the local feeds filled with spam or just too many posts of randomness to follow, being posted every minute to every second at minimum. (looking at you mastodon.social.) Now whether you want 1000+ users, 500 or just around 300 users active in a server, that's your decision and there are server search tools that make it easy to find how many users are in a server.
3) Finding accounts to follow.
Finding accounts to follow on the Fediverse isn't so hard, once you're on the Fediverse, with an approved account. You can search for either, hashtags, specific profiles, or post keywords. You can also follow hashtags, which I use to do, I don't follow hashtags anymore, i'l just follow specific profiles that post enough about a topic i'm interested in to keep my feeds getting over cluttered with everyone's posts based on a hashtag.
4) Understanding that the Fediverse is not just one server, not just one 'platform'. Each platform *and each server has there own direction they may wish to take. Proceed with caution, when joining a server or 'platform'