Go here for a great article on how to assist the holy souls in purgatory as the month of the holy souls, November, quickly approaches. Remember, praying for our departed brethren is a duty, not just another "nice devotion". This is not a difficult thing to do! Even if you simply include them generally in your prayer intentions, offer the first three Hail Mary's of your Rosary for them - this suffices! Sure, you can do many large things for them, but even small offerings of prayer, small sacrifices and mortifications offered with love are so very helpful!