The book should be in English.
Most Helpful Girl
How to Win Friends and Influence People
The 5 Love Languages
The Power of your Subconscious Mind
Getting Things Done
Willpower - Rediscovering the Greatest Human Strength
By Baumeister, Roy F.
The 7 Habits of Highly Effective People
King of the Screwups- this one is a novel
Most Helpful Guy
Self improvement in what area? Just in general or something specific?