Reading a book doesn't assure anything, you've still got to apply it.
I've read a few books on self-improvement, some were pretty hokey, some had genuinely helpful ideas. A general rule I follow is to stick with the classics that have stood the test of time. If a book has been around over a decade and people still talk about it, it's probably got some good in it. The crap soon fades away.
Quick fix/magic bullet stuff is usually a scam. Gimmicky stuff reeks of selling good feelings and nothing else.
A lot of the good ideas are pretty basic. Thoughts can lead to mental habit which eventually will express outwardly in some behavior, so we can consciously entertain thoughts that will lead to desired outcomes rather than haphazardly accepting whatever ideas seem plausible. Things like visualization and affirmation work by keeping your mind focused on what you want, so you'll be more likely to recognize random opportunity, bring the topic up in conversation and create your own opportunities. Belief is by default useful, because you can't give an honest attempt unless you believe something's possible...
I've never heard of color psychology, it sounds gimmicky. Feng Shui is about having harmony in your house right? I admit I like having an organized environment, it's hard to get things done when you're tripping over junk and can't find anything, and a certain peace of mind when everything's in it's right place.