how does steinbeck prapare the reader for curleys wifes death by leenie

Answer 1

Look particularly at the character description of Lennie at this site.
Also read the Themes and Motifs section.

http://www.sparknotes.com/lit/micemen/

Answer 2

There is some background information on Lenny's lack of control of his own strength. Before they got to the town, Lennie had already 'attacked' a woman in a sense. Also, he accidentally killed all the mice and puppies, once again hinting towards his lack of self-control. His attachment towards soft objects also plays a role.