If you've read C.S. Lewis's The Screwtape Letters, I strongly recommend that you buy a copy of Fr. Dwight Longenecker's The Gargoyle Code and read it this Lent. The book is written in the style and genre of Screwtape, in the form of letters from a senior tempter to a junior. There is a letter for every day of Lent, so it makes for simply daily "devotional" reading.
You will not be disappointed... in the book. It may make you disappointed in yourself, as you see the book slowly revealing how Satan might be influencing you — rather than just the fictional (?) persons whom Slubgrip and Dogwart seek to ruin — in parts of your life. (I made it to the bottom of page 7 before I was convicted.) But don't let that disappointment get you down; instead, turn to the Lord and seek His grace, without which there is no overcoming these temptations which the Devil so craftily prepares for us. Now is a most acceptable time, now is the day of salvation!