I use Sync for Lemmy to browse on my phone/tablet. I just browse the Everything category to get a sense of what subs are popular or posting regularly. If I see something I like, I go to that sub and subscribe.
Just be careful doing that in public. There are a bunch of porn subs that post regularly and you don’t want to scroll across one of those while you’re surrounded by people. I usually switch to my subscriptions-only feed when I’m browsing out in public, so no porn subs show up in my feed.