Can you suggest some good self improvement books for teens?

It depends: What are they trying to improve? A good basic book for girls is the "The Care & Keeping of You: The Body Book for Girls" by Valorie Schaefer & Norm Bendell. Many books for adults on self-esteem and dealing with emotional issues would also be helpful for teens. It depends on what the teen is interested in, their reading level, and motivation to "improve".

Yes: Depends on what you intend to improve... Some of my favorites include The Five love Languages by Chapman: The Seven Habits of Highly Effective teens: Almost anything by Joyce Meyer...If you can be more specific, there are other books I can suggest. Self improvement really comes from loving yourself and others...