Tusky is the best Mastodon client by a mile.

You start by finding an “instance” that fits you. There are gardening ones, texh ones, regional ones, fandom ones, whatever. You can easily (and should) join more than one.

Then you hang out on the Local feed, follow people whose stuff you like, follow the people they follow, etc.

After a few days of this your homepage will fill up with stuff for you.

For me, it started slower than Lemmy but I spend way more time there now.