The 3 R’s to improve imagery are: Repetition, Routines and Reading.
You will actually hear children reciting many of the phrases from the stories they have repeatedly heard. This echolalic activity is the result of the eidetic auditory images they hear in their head, much as we often hum a tune that is repeating in our minds.
Routines, of course, are an important source of repetitions. Like re-reading a book, the language used in routines will also be played back to the children as they wend their way through the day.
Reading: The big gun for developing imagery is reading. You start reading to the child a day or so after they are born and you stop when they are 18 or married, which ever comes first.
Initially, you read the same books (for example, Mother Goose) over and over. This facilitates eidetic imagery which will facilitate the child’s analysis of language prosody (melody), grammar and semantics.