You would need to take the time and study the words closely so you can see the difference. For physical things, an image search helps a lot. Your example of sandal/flip-flop/slipper is an unusual example, because these can be regional names for the same thing. For example, we say "thong" in Australia; "flip-flop" is a common translation we use when talking to non-Australians, and both "sandal" and "slipper" make me think of different types of footwear. I wonder if you're confused by the -ity endings for capacity and ability? Look at the etymology of the words, or find examples where only one of the words is correct.

I usually study different meanings of them thoroughly and try to find a uniqe translation for each of them. Split them and study separately.