When I was a brand new Mastodon user I published a post summarizing my experience on how to find people to follow and populate your feed.
@yogthos@mas.to is a good follow for leftist stuff. Posts a lot of good stuff, and reposts (boosts) a lot of other leftists which makes them a great way to discover more people.
toots.matapacos.dog is a leftist server, so looking in the local timeline there is another good place to find people to follow.
Remember that to follow someone on a different server, you can't click 'follow' while on the other server's page. Search for the user (@username@server) to get them in the search results of your own server pages, and follow from there.
Comradeship // Freechat
Talk about whatever, respecting the rules established by Lemmygrad. Failing to comply with the rules will grant you a few warnings, insisting on breaking them will grant you a beautiful shiny banwall.
A community for comrades to chat and talk about whatever doesn't fit other communities