I am a little over a third of the way through reading St. Teresa of Avila's Life. Here are some virtues she spoke of and one tip on praying she gave:
(1) Not speaking evil of anyone, no matter how slight; avoiding all fault-finding (not desiring to say of another person what I would not want him to say of me); no talking behind another's back (ch. 6).
(2) Pray not with the noise of words but with longing that God hears (ch. 15).