Yeah, I've started just posting anything that seems interesting while trying not to flood the place. I'm pretty deep into the tech world so it's been mostly tech, but I'd highly recommend posting content that interests you and I'm sure it'll interest others.
If you're using a lemmy web interface (as opposed to an app), there is a cross-post button you can use to post in other communities that are tanginately related (if you decide to create a community for your topics).