Pick any word at random (noun is easy): let mind play freely around it until a few ideas have passed through. Then seize on them, look at them, & record. Try this with a non-connotative word, like “so” etc.
Systematically eliminate the use of certain kinds of words or phrases from a piece of writing, either your own or someone else’s, for example, eliminate all adjectives or all words beginning with ‘s’ from Shakespeare’s sonnets.
Systematically derange the language, for example, write a work consisting only of prepositional phrases, or, add a gerundive to every line of an already existing piece of prose or poetry, etc.
Rewrite someone else’s writing. Maybe someone formidable.
Get a group of words (make a list or select at random); then form these words (only) into a piece of writing -- whatever the words allow. Let them demand their own form, and/or: Use certain words in a set way, like, the same word every line, or in a certain place in every paragraph, etc. Design words.
Never listen to poets or other writers; never explain your work (communication experiment).