Self-improvement, to some degree, requires self-awareness. Self-help books try to bake some of this in, but I think ultimately having the ability to see your "automatic thoughts" and understand their motivators. I think this is the realm of cognitive psychology, and I think they use many tools from that in self-help books -- but from what I've had recommended by well-credentialed folks is "Feeling Good" (horribly trite title for a great book) by David Burns. It describes itself as a therapy for depression, but what it does is quite thoroughly and methologically lay forth the principles of Cognitive Therapy as created by Dr. Aaron T. Beck at the University of Pennsylvania. Burns was one of Beck's students (both MDs and clinical researchers).
And obviously waaaaay before that there was Astanga Yoga where self-awareness is a big part. For Covey the Seven Traits of Highly Effective People might be obvious, but as we deconstruct it, we see that he's a Mormon, and therefore may live a fairly "idyllic" life free from of the vicissitudes (or fun) that some face, simple and wholesome values, and with a lot of positive thinking going on around. For those wondering why adopting those traits may be harder than just "wanting to," I think self-awareness is key. Know thyself... For example, I do not like fishsticks...
