Self-help books and articles are everywhere. Should a Christian grab a book off the shelf or click on an article that encourages this? Sometimes Christian books and articles even seem to have a strong feeling of self-help.
The answer to this question depends on the person and how a person approaches these types of writings, because it's likely that parts of it should be ignored or disagreed with but other parts may provide some helpful points. A person who is able to know what to disagree with and what works may possibly find these slightly helpful. And, of course, there may be some books and articles that you can tell right away aren't as helpful as others, and those can be passed on.
One part of these that should be ignored is sentences that start with, "You deserve ... " As Christians, we really can't say we deserve anything. We feel grateful for all the good things in our life, recognizing God's daily help in our lives. And, it's really Jesus who is deserving, not us. We should regularly be thinking how great God is to save sinners like us and how he continually helps us grow.
We should have confidence in ourselves in some way, though, but not in that we deserve anything, but in that we are created in God's image and are given a beautiful mission from God. God wants us to be confident in that we are his children, and we are valued in that way. People who struggle with self-confidence may be somewhat mean to themselves but treat others well, or lack confidence in themselves but have lots of confidence in others. God would like us to respect and love all people, including ourselves. So there is some importance in thinking of one's self and being good to one's self, as long as that's not the only focus of a person.
Parts of self-help books and articles that are helpful could be some pointers here and there that have similarities to the Bible. For instance, one may say to focus on the positive things in life and try to not think negatively a lot or be around negative people. That's a great reminder of Philippians 4:8, where it tells us to think on good things. I even read a book that wasn't labeled as Christian that had advice for work that had this advice, that too much negative can be very unproductive and difficult.
I'd recommend, if a person knows they want "self-help," to not necessarily go to these types of writings, but to find something that really focuses on God's great, unconditional love for us but still acknowledges the fact that we are sinners and imperfect in this life, but God's helping us (sanctification). It's a healthy balance. To grow, we need to know we are imperfect and what areas we need to grow in, but to also not lose hope, we need to remember how forgiving and loving our God is, and his help in our lives. I've enjoyed reading Martyn Lloyd-Jones and would recommend his writings if you can't think of any author/preacher right away.