I updated the short list of recommended devotional and study helps in my How to Become More Christ-like booklet. Those that don’t read devotional books on practical Christian living and don’t have Bible study helps are at a disadvantage.
Here is the short list:
Devotional Books: The Imitation of Christ by Thomas a Kempis; Power Through Prayer by E.M. Bounds; Perfect Love by J.A. Wood; Plain Account of Christian Perfection by John Wesley; Pungent Truths by B.T. Roberts; A Serious Call to a Devout and Holy Life by William Law; Dying Testimonies of Saved and Unsaved by S.B. Shaw.
Study Books: Strong’s Concordance; Harmony of the Gospels; Smith’s Bible Dictionary;
Bible Software: e-Sword (free at e-sword.net).