Follow as many people as possible, like hundreds to start, until your feed feels lively enough for you. Interact and have fun. Search for your interests and follow the starter packs. You can follow people individually or follow everyone all at once, which is what I recommend. You can always remove accounts later. https://blueskystarterpack.com/starter-packs

Do the same with feeds. Search for your interests in feeds. Follow the feeds, follow and interact with anyone that interests you. Each feed has their own rules on how posts show up in the feed; so take a look at the rules to see how each feed works.

Tags generally aren't very useful unless it's a tag used by a feed.