I'm still a Lemmy noob myself but I wanted to give a few tips/hints to make using Lemmy/kbin/fediverse easier.
Note; I'm putting this together quickly and there may already be other, better guides and help pages, so please link them in the comments if you know of them!
1. You don't need multiple accounts on different Lemmy instances
(instances are servers, they are different Lemmy websites. lemmy.world and lemmy.ml are 2 different Lemmy instances)! Federation means the servers talk to each other and show your messages to people on other instances.
2. Remember, This is all BRAND NEW!
We have teams of developers working on it constantly, fixing any bugs and making it easier to use. Stick around and you'll notice things start getting so much easier to do. Patience is the greatest virtue you can have here!
3. USE AN APP!
The Lemmy web interface isn't great, and it's more confusing than intuitive. Installing Connect for Reddit yesterday improved my Lemmy experience twice as much instantly
Popular apps:
Connect for Lemmy (Android) - opens in App Store
Liftoff - A Lemmy for Windows , Linux and Android
Jerboa - A native Android app made by Lemmy's developers (Jerboa IMPORTANT NOTICE: Jerboa was crashing on some instances (instances are like lemmy.world, lemmy.ml) because of an upgrade issue. If it crashes for you, try something else for a couple days until it's fixed)
Lemoa - A Gtk client for Lemmy on Linux
4. Find your communities!
Took me a while to find this community. Thankfully there are Lemmy Community Browsers that let you search for communities across instances! There are 4-5 more browsers, including ones that say whether an entire subreddit had migrated here, so please feel free to post them in the comments!
I was going to post a lot more but I'm short on time and need to run and some of my post was deleted. If you have any more to add, please do so in the comments and I'll edit this post!