Decide what you really want to write about figure out your nice and master that. It?s not to say that you cannot write about different things, or tackle different types of writing, but know what it is that gives you the impetus to write and brings out the best . I would never write about academics, for example. It bores me and there would be little point in the investment of my time in such a field that is time sensitive. For a book fan however, this would be the perfect topic. Improve just by thinking, reading and research well so that you know the subject well as only then shall you be able to do justice with the content.