First off, make sure that you take account of the style and tone of what you are reading, as well as the content. Read carefully – it’s your best guide to how you should write yourself. To take one example, some students report that Charles Darwin wrote a book called On the Origin of the Species, rather than On the Origin of Species. This of course makes a mockery of Darwin’s argument, which is about the dynamism of species, not the unity of the species (the human race, or whatever). This is one of the most famous books in the English language, so students can only distort it through not paying attention – reading the words, that is, but not properly understanding them. However, don’t think that just because something is written down in a book it is correct – mistakes slip in all the time to published work. If in doubt, ask your supervisor.
Reading widely, as well as precisely, is crucial, not only because you will gain a better sense of particular topics than by relying on a small number of sources (such as Wikipedia). A vital part of your University life is in developing a sense of intellectual curiosity – not just reading for the purpose of extracting information, in order to write an essay, but to enlarge your understanding more generally. Students are, arguably, increasingly reluctant to move off the prescribed reading, whether through lack of time, or fear that they are wasting their efforts; but it is always worthwhile to read around the topic, to explore issues that you don’t immediately understand, to clarify and contextualise. This includes paying attention to contemporary media, such as newspapers and news websites, which on any given day will have relevance to much of what you will be learning in the lectures and supervisions.