Always check to see if you can pull the faceplate off

found on Acid Cow

You often can pull the faceplate off if a skimmer has been installed, but they're usually much smaller than this. 

Card skimmers hate this one weird trick

from here and here (image source)

Don't be dragon your feet about it either. It's your money at stake.

That's one way to MITM an ATM

found on Meme Base

Always check your ATM for anything that might come loose. It may have been placed there by some crook to steal your account information.

I've heard of fake faceplates before but this is ridiculous

from here (image source)

I wonder if Brian Krebs has covered this style of ATM skimmer.