Of

A preposition. Once you’ve put one at the end of a sentence, it’s a habit you’ll never tire of.

Anywhere else in a sentence, it is indicative of tortured writing. See: I just did it there. I said “it is indicative of tortured writing” when I could have said “it indicates tortured writing”. This is a kind of nominalisation (though strictly speaking it is adjectivisation) in that it guts a perfectly good verb (“to indicate”) replaces it with a more boring verb (“to be”), turns it into an adjective (relating to the subject of the sentence “to be”).

Other mendacious uses of “of”: look out for the character string “...ion of”. This is a dead giveaway for a passive nominalisation. For example, "In the event of a determination of an Event of Default by the Non-affected Party..." — makes you wewep, doesn’t it — can be less tiresomely (and ambiguously) rendered as “if the Non-affected Party determines there has been an Event of Default”