dewline | Maps: Looking For Resources

Okay. Now I have QGIS on my new-ish Mac Mini, and I've started downloading Shapefile data because that seems to be a thing you do when you have GIS software that you intend to use. Some of you are on my friendlist because you've provided insights on map design over the years, and I am wondering what else I should be looking at and looking for. This is a hobby of mine that seems to have made me slightly more useful in my most recent day job, which I consider a good thing. I want to keep building on that.