1) In the month of Elul one should concentrate on strengthening oneself in three areas: 1) Repentance, 2) Prayer and 3) Charity. These concepts are alluded to in various verses whose first letters make up the acrostic “Elul”, as follows.
2) The verse “Umal Hashem es levavecha ve’es levav zar’echa” (And Hashem will circucize your heart and the heart of your descendants!”) alludes to repentance. The verse “Ani ledodi vedodi li” (I am for my beloved [Hashem] and my beloved [Hashem] is for me!”) alludes to prayer. The verse “Ish lerei’eihhu umatanos la’evyonim” ([sending portions of food] each man to his friend and presents to the poor) alludes to charity. (Kitzur Shulchan Aruch 128)