Ideally in a campaign your rad ideas for the low levels should be encountering really really low-level minions of your main villain. Take your super epic high-level main baddie, and figure out what his little side projects are. Work the layers down and down until you get to the street-level grunts doing the really minor dirty work which SOMEone needs to do, but the higher-ups don’t want to bother with — like, I dunno, laundering their secret society robes. Have your players fight those guys and tailor the results of the encounter to grip them with whatever hook’s going to work to make them want to get deeper into the story.