I've bought many self-help books in my lifetime. These can be very useful at times, sometimes they
help point you in the right direction. They can be fun, and they are often just plain funny. And some of them are not worth the cost of the paper they are printed on. Self help is okay, but glorifying self above all else is not, and a lot of these books do that.
My advice is don't waste your money on these. If there is one you want to read, check it out of the library. I think we have to be careful. I have a list of Christian self help books that are great, uplifting, and these have been worth the money I spent on them. I also have many that I was disappointed with, written by well-known people, experts in their fields of study, yet they just struck me a being way too 'self' centered.
You already have the only self-help book you will ever need. It's the Bible. If you don't have one, go right now and buy one. A good, sturdy one. Keep a pencil or pen with it because no matter how much you vow to not write in the margins and highlight this verse or that, you will. I have many Bibles, all over the house and in my car. I also have pieces of a Bible that I wore out-I used it so much, it literally fell apart! It's very close to my heart, though I don't use that one anymore, because it was with that one that I really met Jesus.
Blessedly, when we arrived here on this planet, God supplied us with an instruction manual. The only instruction manual and self help tome we will ever need is the Bible.