Roland Barthes wrote in his 1967 essay 'The Death of the Author' that "To give a text an Author" and assign a single, corresponding interpretation to it "is to impose a limit on that text." In other words, it is artificial and ultimately purposeless to interpret a text only as a something produced by someone for a singular reason.
There is no 'right answer' when it comes to interpreting a text. Indeed, suggesting that there is would be to assume that there is only one type of reader, which we know is not true.
Releasing ourselves from the need to find out 'what the author meant' empowers us as readers to understand texts in ways that speak to us at a particular moment in a particular place. However, it also transfers responsibility for our understandings to us rather than some faceless writer on whom we can place all the blame. As Literature students, you need to be aware of how and why you take the meaning you do from what you read.
We can, of course, take into account the purpose, context and audience of a text when we make a reading. However, these are only some aspects of how we might come to make meaning of what we read and see.
A reading practice is the system or process we use to come to an understanding of a text. Sometimes we can label this system with a word like Marxist or post-colonial, but this is not a defining feature of a reading practice. Another way of thinking about it is as a lens that we look through in order to highlight particular aspects of the text.
The way we read is a learned process. It is generally something we sub-consciously do. Literature students must become conscious of it.
Your ability to read a text in a variety of ways, thereby proving your mastery of the subject, is directly related to your understanding of your world. Make sure you read widely and do your research when it comes to things like Marxist readings and feminism. It's a little bit interesting as well as useful!