Vocabulary is best built through roots and repetition. Knowing that "biblio" means book and "phile" means lover gives you bibliophile without memorising it separately.
One-word substitutions are a standard section: a person who loves books is a bibliophile, one who talks to himself is a soliloquist, and a government by officials is a bureaucracy.
Idioms must be learned whole. "Once in a blue moon" means very rarely, "to let the cat out of the bag" means to reveal a secret, and "a blessing in disguise" is an apparent misfortune that turns out well.