Let's talk it out
There are lots of hue and cry about what to read and from where when it comes to Ethics, GS4, preparation. Here is simple and concrete guideline:
With above preparation anyone can go to ethics paper and write good answers(Try this in some mocks). You need to use as much as possible ‘keywords’ and Articles of Constitution from above mentioned sources.
For Quality improvement:
For Ethics, more than knowledge, you should depend on application of knowledge which you, and we all, already have acquired from Polity, Newspapers, Essay, and Society part, even from history.
All the best.