If you get a small pebble/twig/chunk of plastic stuck on your foot, it will behoove you to remove it, else return home with a pebble/twig/chunk of plastic-shaped blister on the bottom of your foot that will be hard to explain. And UGLY.
If it looks wet, do NOT run through it. There are too many possibilities of what it might be to even risk it! Think bodily fluids of people and animals – don’t try to figure out what it is, just go around it!
Run your route in shoes first, and look for possible dangers to bare, unprotected feet. Are there sections of gravel? Dirt? Glass? Debris?? Detours?!? These things are helpful to know BEFORE you start running a new route.
The next lesson will focus on grass. Yes, grass. Grass may look nice to tired feet, but there is more than meets the eye when it comes to grasses.