There is a wonderful tool in the little red book called Treasure Path to Soul Winning.  It will help the believer to be able to open to appropriate verses as the need arises.  It includes three sections with twelve assignments to memorize in each.   Each assignment has five verses given with a short label to help fix it in the memory. 

Section 1: Salvation Explained

Assignment 1: Best Text to Arouse an Interest in Spiritual Matters

Life is brief: James 4:14
Life is uncertain: Proverbs 27:1
Death is sure: Hebrews 9:27
Christ may appear any moment: Matthew 24:44
No escape for procrastinators: Hebrews 2:3