anyone else find knowing what keywords my competitors are using harder than the guides suggest?

yeah because the guides assume you've got ahrefs or semrush. without a tool: look at their page titles and H1s, that's what they're targeting, and type their main topic into google and see which of their pages come up. the free tier of ahrefs only covers your own site. if you can swing one month of a paid tool, export the organic keywords for your top three competitors, filter out their brand terms, and you've got a year's worth of ideas. then cancel it.