The first thing anyone must do before any other self improvement is even logically possible is doing something about self deception, otherwise any self improvement attempts degenerate to be a form of wireheading as you will self deceive as to what the self improvement achieves, and you would end up improving your ability to self deceive.

I would suggest dropping this belief in silver bullet self improvement, burying it, and putting a stake through it's heart, as the first step. If you look at the accomplishments of people who couldn't just improve their subjective performance by improving ability to self deceive - technical fields for example - about the only type of self improvement you see is training, on complicated problems, with tests.

The self deception is a cognitive process that we are reward/punishment conditioned to do, internally, when doing free form non-externally verified thought. E.g. a Christian would be subject to anxiety-like feeling when considering the arguments against the Christianity, and reward feeling when coming up with arguments why Christianity is right, and would get conditioned to feel good about invalid approach to reasoning and feel bad about valid approach to reasoning. Quitting religion won't reverse this conditioning. The conditioning could perhaps be reversed by studying mathematics for long time and doing the exercises (and getting punished for self deception as self deception would be resulting in failures), or some similar occupation where there is reliable external verification of correctness.

edit: Sorry, christianity is only meant as an example. This applies to any other ill-founded belief, religious or otherwise. The same can also happen the forms of atheisms that include belief in validity of an invalid reason against existence of god. The christianity is simply a world's most popular religion at the time, and by far the most popular in the developed countries, and so it is an important case.