A very brief daily prayer each day for nine days. For the more ambitious, say a Divine Mercy Chaplet also (I can guide you to some very good ones, audio or video, if interested). There is also a link at the following site.
“Today bring to Me the Souls of those who have separated themselves from My Church,and immerse them in the ocean of My mercy. During My bitter Passion they tore at My Body and Heart, that is, My Church. As they return to unity with the Church My wounds heal and in this way they alleviate My Passion.”Read more: http://www.ewtn.com/devotionals/mercy/novena.htm#5#ixzz1rdpvS7zf