I'm a follow directions kind of guy, so when a soup recipe states, "... skim ..." I want to skim, but with what? What do you use to skim your soup? Do I need a perforated spoon kind of thing or a wire mesh kind of thing, or what?
If you are not in a hurry, the easiest is to let the whole thing cool in the fridge. You'll be able to remove the disc of solidified fat with a spoon. If it's something like chicken fat, you can and should save it in the fridge/freezer for frying potatoes.
For immediate results, swish a cold leaf of lettuce or cabbage on the surface of the soup. The fat will solidify on the leaf. Or do the same with a frozen container of water. Or lay a paper towel gently on the hot surface, lift off, discard, repeat with fresh towels as necessary to remove the fat.
Exactly what TeRReT said. You can use a spoon or ladle to skim. Or you can use a very fine wire mesh spoon, which also works. Ice cubes in a towel also work.
If you're skimming the fat off the top of the soup, a ladle or some other non-perforated spoon should be used. I took an inexpensive large spoon and bent the handle up to make it easier to skim. I prefer using a spoon rather than a ladle because of the spoon's more shallow profile.
If you need to skim off foam/scum and other impurities, then a fine-meshed skimmer is used to allow the soup/broth/stock to flow out of the spoon, leaving the impurities in the mesh skimmer.
I've used paper towels, believe it or not. Let HOT soup sit a bit till oil/grease is pretty much all on the surface. I usually fold paper towel in quarters, lay on surface for a short time... you'll see the grease getting absorbed. Then I lift off with tongs.