This is very easy, and yet remains a major problem for many - the (in)famous) authorial fallacy.
The question really is: To whom does the text belong? Who owns the text once it has been published? ('own' not in the legal sense of ownership of course, but in the literary sense)
Culturally, we are used to thinking that a Shakespeare sonnet belongs to Shakespeare, and as such, Shakespeare knew best what he wanted to do, and so he went and did it: the role of the reader is to see that, to enjoy it - to receive it, as it were. The sonnet exists independently of its readers: its meaning (whatever that may be) remains unchanged, dormant, waiting for each reader to discover it. Now the reader is like a gold-miner: the job is to dig until the gold we know is there ('what the author meant') is found - everything else we find is irrelevant if it's not gold.
But this is obviously a fallacy when it comes to reading: whatever Shakespeare 'meant' is unknowable (he did not leave any commentary on his poetry), it is context-dependent and culturally charged. And really: if on your way to the gold you find rubies, sapphires, platinum and jades - are you really expected to ignore them?
The reality is that the text belongs to the reader: if you can convince yourself (and others) of this, you at once free the reader in you. As long as you believe the author knows best, is always right, and had a definite plan, you will confine your reading and thinking to the author and will not engage with the text - yet the text belongs to you. The problem starts with the professionalisation of literature, and the creation of experts - but those experts are readers like you and me, it's often only because their interpretation came first that it has become enshrined in manuals. Yet a question is: why would they be more right than you?
Imagine that an author wrote a text with a very definite theme (= 'message') in mind (for example: 'Love conquers all'). Now imagine that, reading this text, what strikes you is that what you keep thinking about is : 'Friendship is stronger than anything in the world'. The 'Love conquers all' idea does not occur to you, instead what you take away from the text is that idea of friendship, not love.
The question is: who's right, who's wrong?
Are you wrong, or did the author mis-judge their own text?
Did you fail to see something, or did the author fail in putting it well enough?
A way out of this situation is, once again, to see a text as full of potential meanings, i.e. full of potential ideas. These ideas might be as varied as there are readers, because the reader owns the text.
So there is ONE text, and MANY readers; there is ONE text, and MANY interpretations. Take ownership of your reading by considering that a text is nothing more than ideas arranged in story form: free your mind of the authorial fallacy, and your interpretive skills will grow a hundred-fold.